Questions about endings mechanics

Hello

I’ve done the first ending where you kill grandmother silk in act 2 and bind her into hornet transcending after.

I’m now going and trying to do the other endings and go into act 3 that I know that exists. My question is if there is any mechanic that I should look out for that would lock my save from doing the other endings and if it’s avoidable.

(Try to answer without huge spoilers if it’s possible, understand if it’s not.)