Thank you so much for your comment.
Indeed, the increase in difficulty needs to be reviewed. For the moment I am simply increasing the number of enemies but it should certainly be smoother and not just increase the number but also play on the type of enemies, life points, damage etc...
I see what you are talking about regarding life points and indeed there is a problem with updating the life bar. I didn't update it after the level up screen and so it only updates with the next damage taken.
Thanks again for you feedback.