I think the only genre fatigue that really exists is on an individual level. As a reader, I once binged on m/m alpha/werewolf for several months. It felt like I read everything out there (obviously, I didn’t) and it exhausted me. I needed a break, so I jumped to a different genre. And then I jumped back!
I would hate for someone to think there were too many stories in a particular genre, so they didn’t write one! I want to find the next excellent story to binge! What a sad day if any one genre stopped growing.
There are so many unique ideas, phrases, characters, arcs, etc to let them go to waste.