I put a mirror to Leaf's tank a couple days and he went mad with flaring. When he pulled his gills forward I saw about 4-5 layers of the red filtering gills. Is this supposed to happen? I don't really remember with other fish.

I think it is possible. Some bettas can flare their gill covers far out while some just stick the beard out. If he is breathing fine and acting normal, I wouldn't worry about it.

That's what u suppose to see when a betta flares anyway. If the red thingies are absent when he pulled his gill plates forward, then something is definitely wrong.

Yup it is normal . That is what my Zeke does when he flares and they are red underneath, that is normal too

Okay I guess I just did not notice before. I thought I heard that you only see the red layers of the gills on dead, cut up fish. Leaf is definately not dead or cut up!