Solid game.
I would only say 2nd boss tail thing felt a bit unfair, because you can't predict where it will dig out, so if it digs out right under you, then you are garanteed to take damage.
Also boss transitions felt a bit too long, cuz tbh at first I was also thinking that maybe something was bugged or I have to do something specifically to proceed. Perhaps could slowly fill boss hp bar to full, while transition phase is happening, so player would know they didn't stuck and something is happening. As bonus, player will know for how long they need to survive till phase 2.
Also had WebGL out of memory error (Chrome), cuz of which had to restart the game, but when I tried to not use fullscreen it seems to fix itself.