Hi, another person had the same problem a few months ago.
I'm not sure what the problem could be, I think it depends on the fps. When I made this game I probably didn't even know how to manage movement and camera based on fps.
This was a one-week project, so I don't think I'll fix it, but I'd like to create other games with this combat system in the future so I appreciate immensely the feedback. This is absolutely a thing I have to look at for the next games. Thank you very much!