So apparently, eevee has a new gender difference.

From Sword and Shield onwards, all female eevee would have the white tip of their tails cloud-like instead of them being jagged like the original eevee. (According to bulbapedia)

This was first seen in Pokémon let's go on your partner eevee's tail if you had a female.

Apparently, it has become canon for all female eevee to have that cloud-like tip now.

I don't know if it's a good or a bad thing.

Oh well, I'll just miss the time there were no gender differences between eevee.