in FnaF 2, Withered Foxy is ALWAYS active even if you set his AI level to 0, this is to make sure the player can't just avoid the real difficulity of dealing with him, and also to not make BB useless in challenges where he's active but Foxy isn't, since his main purpose is to let Foxy kill you

when the mobile version was being created, this was thought to be a bug and in the old mobile version, Foxy was completely inactive if his AI was 0

in the remastered version of the mobile version, this was fixed, along with all mobile bugs