Is it permissible to eat the food of an innovator (Mubtadi') at innovative occasions that have no authority from Allah?

Participating in innovations (bid'ah) and innovated (bid'i) celebrations is a reprehensible act and is impermissible. As for eating the food of the people of innovation at these celebrations without participating, its ruling varies according to the type of food:

Other than slaughtered animals: It is permissible to eat from it if it is from the good and lawful things (tayyibat). Slaughtered animals: It is impermissible to eat from it if the slaughterer intends it as an offering to other than Allah (such as the Messenger or others), even if he mentions Allah's name over it, because the primary intention is for other than Allah. This is among the definitively forbidden things, as Allah Almighty says: "He has only forbidden to you carrion, and blood, and the flesh of swine, and that over which any other than Allah has been invoked." It is permissible to eat from it if the slaughterer intends it merely for celebration and slaughters it for Allah Almighty and mentions Allah's name over it, even though the act itself is an innovation, because it was not slaughtered for other than Allah.