Congrats on getting the game in for the jam! (even if it wasn't on time, my teams submission wasnt either lmao)
I feel bad because I don't want to rate a game harshly just because it frustrated me, so I'll start with some decisions that I liked.
I think the decision to have the birds not deal damage, but only "confuse" the player is nice. It leads to a few situations where the player can decide to take a riskier path to avoid getting hit, or just take the confuse to avoid taking damage. The game also has nice progression where you start with the fish, then the birds are added, then the octopus comes. A smaller but still good decision was giving the player a bit of control of their jump height by holding down spacebar. I do wish there was a little more control (able to go higher or lower), but having any control is good in a game like this.
However, there are a few game design decisions and oversights that made the experience feel a bit unfair, mainly in the sense of communication. (Note: this is all my opinion so grain of salt of course)
Firstly, it is hard enough to dodge the fish when you can see them, but not knowing if they will appear right under you makes it even worse. If the player has no way to tell where a fish will appear or no warning it becomes much harder to make informed decisions and can lead to it feeling random, or player feeling cheated. Secondly, the reverse controls effect, while cool, needs a bit more in terms of telling the player when it will end, or at least not punishing them for holding a direction when it ends. There were multiple times when I was playing where I would be holding forwards to go backwards, then the reverse would end and I would run into the fish anyways. There is also a bug with the reverse controls where if the player gets hit, their pallete is set back to normal but their controls are still reversed. Finally, the octopus needs some sort of animation or warning before its tentacles come down. In a game as chaotic as this, a little animation or something to draw the players eye to the tentacle that is about to fall is very helpful to help the player have the best chance to react and plan around what is about to happen. The hit box for the tentacle is also pretty unclear
Other game design decisions that soured the experience included: pretty large hurt/hitboxes for the player and enemies which made it feel like I was got hit in places that I shouldn'tve, fish generation that felt a bit unfair, the player falling much faster than the fish leading to me running into fish I thought I had already jumped over, and a lack of sound giving less immersion and weight to actions.
Apologies for the wall of text, again congrats on finishing the jam and making games!