This is a pretty solid start, but I can think of 3 good ways to improve it as you go along.
First issue is the combat doesn't feel very impactful because of the lack of tactile feedback on hits. Adding sound effects and maybe the enemy flashing could do a lot to help with that, but you might also want to reexamine the core combat controls to make the player's moves feel more deliberate. As it stands, you can easily beat the bosses just by circling around their attack areas and flailing at them with the fire sword. The player has a bunch of moves but there's little reason to use the more strategic options yet.
Second change would be to fix the camera. It clips through a tree in the opening cutscene and it clips through walls in the second arena, making it impossible to see from certain positions. I don't know how it works in Godot, but there should be a way to add hit detection to the camera so it doesn't go through walls. You could also make the foreground objects transparent so the camera can go out of bounds but the player can still see. Also, just move that one tree in the intro, it's in the way of the camera.
Third change is probably the most important, and it's something going on under the hood. The enemy attacks and especially the player's special move are spawning and destroying special effect objects, which causes the game to freeze for a few moments every time it happens. The way to fix this is to spawn all the special effect objects you'll need when the level loads and keep them deactivated outside the map. Then when you need them, instead of spawning the object you teleport it into place by setting the object location, and when you're done you teleport it back to its holding position. This should stop the freezing completely because nothing's being created or destroyed.
Also, I did need to mark you down for devlog consistency and clarity, since you didn't have any devlogs on your game page and the description seems to be for a different game of yours. Also, I understand English seems to be a second language for you judging by the parts of the game text that are untranslated, so if anything I said during this doesn't make sense because of a language barrier, please let me know so I can clarify. This game looks like it could become really good, you just need to fix a few things with the foundation first.