This may seem a bit nitpick-y at points, but trust me, I only do so so that I can give you a better idea as to what you might be able to improve
(Also yeah, this is pretty late but I've gotta start somewhere
)
=== Gameplay ===
//Readability
How well am I, the player, able to determine where to go without trial and error? For the most part, your level does not have a problem in this regard; that is, I was able to clearly tell where to go for most of the level. However, there are some parts of your level that do have some problems. For instance, the yellow and orange 'waterfall' tiles tend to blend together with the spikes. There isn't a strong enough contrast between the two, so I found myself accidentally hitting spikes that I couldn't quite discern from the background (at least in my peripheral vision). For spikes and other obstacles, I always recommend making them stand out strongly from the background, usually by simply making the outline of the spike/saw/whatever have a strong outline color. Here, though, the orange outline of the spikes is also used in the background. The other
major problem I found is that your counter, used in the mini-coin section, is placed on the far right of the screen, right where some of the gameplay is. A better way to implement this is shown in Fingerdash (the official level, which I'm assuming you kind of based it off of). In fingerdash, the counter is smaller, higher, and slightly pulled away from the edge. It also properly overlaps everything and is a completely different color. This isn't a 'levelbreaking' problem, but I would double check all your design elements and make sure that they don't overlap crucial gameplay (I'm mainly referring to the upper portal that the player can pass through to get the first mini-coin). Other than that, there are no problems with readability in your level.
//Layout
This section refers to the overall composition of gamemodes and how they play. There are a few problems I have with the gameplay itself, ignoring synchronization. For the most part, your level is not super difficult. Mostly, there are a few gameplay segments that just feel a bit awkward. For instance, the red pad/green orb/reversing dash orb setup at 11%. It's way easier just to skip the red jump pad and the green orb, just jumping over them to hit the dash orb. It even syncs better with the music that way. You seem to have acknowledged the possibility of the player doing this by adding normal gravity portals at the top, so my question is why even bother having the jump pad and green orb there? It convolutes the gameplay more than it helps it. At around 31%, it is possible to simply miss the portals at times (which just feels awkward, as the portal doesn't seem like it should be miss-able). 44% is probably the best example of this; the player literally has to jump into the wall, where there is an invisible teleportation portal that sets them back properly into the level. There is absolutely no indication that the player needs to do this. At 51%, it is sometimes awkward for the player to line themselves up to hit the dash orb with the ship, especially if they went for the mini-coin earlier. Also, the position that the player ends up in (reverse gravity on the ceiling) was incredibly awkward, but that may seriously just be me, I can't really tell. At 79%, the gameplay is really kind of tedious, as it's hard for the player to really tell where they're going to end up. Normally, this would be fine in a difficult level, but your level is not really difficult to the point where forcing the player to memorize where they are going to end up is warranted. Remember when creating a level that, as the creator, you specifically designed the map; you know exactly what to do. The player does not.
I would like to point out that there are quite a few parts I enjoyed in your level, though. 58% was very nice and synced well, the 38% dual was fun once I got the hang of it, and most of the stuff before that point was also fun! So don't feel bad about my overly in-depth qualms with the other parts.
//Synchronization
Now, for the most part, the level is not synced terribly, but it isn't synced super well either. There are some exceptions, such as 58% as I mentioned above; it was synced very well. For most of the remainder of the level, there were a lot of components that just really didn't work well with the music. At the beginning of your level, the random black and white fades were not really synced to anything. At 33%, the random teleport up and then back down is really disorienting and again, barely syncs with the music. The level slowing down at 58% works well with the music, but the level does not speed back up with the music at 61%. From this point on, the level feels a bit awkward sync-wise, as the music is upbeat and quick while the level is played at a slow speed (though gameplay itself is synced fairly well at this point). It isn't until 70% where the level randomly speeds back up, from slow to x4 speed. This does not sync at all as the music is still the same as it was when the player was at slow speed. There are a few other places that aren't super notable where the sync doesn't quite seem right. Whenever you are designing a level, try to keep synchronization as your key priority, as GD is mostly a rhythm game. The better the players' mouse clicks and icon movements match the music, the better the level.
Always keep this in mind!
=== Design ===
//Block Design
This section is specifically about the design and layout of the blocks. The structures themselves are fine in your level; however, the block design is rarely, if ever, anything more than just default blocks. Generally, to spice up your block design, you're going to want to add some extra flare to the default blocks. As many people tend to do, you could use a flat color block as your base and add various other decor to create a unique block. On the bright side, you did vary the blocks throughout, which is essential. If you don't change the block design throughout your level, it begins to feel bland and low-effort very quickly. That being said, your block design just isn't really unique enough to the point that it catches anyone's attention. For this category, I would definitely recommend checking out the successful level creators (funnygame, serponge, etc.) and observing how they create intricate (and sometimes simplistic but interesting) block designs.
//Additional Decoration
The remaining decor, such as effects and "air" decoration. This section could definitely use some work. There isn't a whole lot to look at beyond a few basic backgrounds and flare added here and there. It tends to be in your best interest to fill up as much blank space as possible without overwhelming the player, unless overwhelming is the kind of look you're going for. Try to find areas that are out of the player's path to add more detail. As the game ages, peoples' expectations rise. There is nearly a requirement, at this point, to have your level be more "fluid" and synchronized with the music. One of the best ways to improve this category is to add effects that sync wit the music! It seems obvious, but I have seen multiple occasions where creators ignore this potential and just randomly add backgrounds that don't really lend themselves well to the music. Overall, focus on adding more decor to fill up empty space, and try to come up with some cool looking backgrounds to spice up the level in general. Again, it's not a bad idea to look towards popular creators for inspiration (obviously do not copy them exactly in a level you publish).
//Colors
Your color choice is not bad. However... there really only is one color choice. The colors rarely change throughout your level; not even in response to the music. Scrolling through your level, the background never changes color except for the black/white fades in the beginning (which don't really match anything in the music, as I said before). There aren't a whole lot of flashes or color changes throughout the entire level, and there are quite a few points where I could easily see some change in color being incorporated. I understand there is a theme you are going for, but there are still more colors/shades you can use to add some emphasis to your level. Right now, it just seems kind of "dead" compared to a level that feels alive and vibrant as it ebbs and flows along with the music. When you're in the design phase of your level, definitely nail down some color palettes you like, but remember not to stick to it too rigidly. Mess around with color triggers a bit and try to add some sync with the music, it will make your level much more alive.
=== Conclusion ===
By no means is your level bad. In fact, it is definitely better than others. I tend to bring up a lot of negatives in my reviews, to show you how I think you may be able to improve your levels. You don't have to take anything by heart, but external opinions are often one of the best ways to improve your work, granted they have actual criticism. While your level lacks in more of the advanced aspects of level design, you definitely have a good base to build off of. Focus more on sync with both gameplay and design, try to add a bit more flare/uniqueness to your designs, and
really playtest through your level. I'm talking multiple times in a row. Get a feel for it, and if anything feels off, even slightly, try to correct it. It's definitely not easy to fine tune a level that much, but it pays off in the end.
Overall, I would categorize this as "Decent".