If you find a magic cure, let me know. I'm stagnating too. I was once told by a former manager that not everyone has the potential to be more than a midlevel developer.

My guess is that comment doesn't apply to you and that you are working in a marketable technology (I'm not) so you could probably switch companies. That will give you a fresh start that could give your career a jump. I would guess that moving from a midlevel FAANG role you could move into a senior role at a non-FAANG company. I'm not sure if that would be consider a positive career move or more a lateral one.