From what I've read they use fetal bovine serum to grow the cells -- which kind of defeats the purpose if you're a doing it for feel good reasons.

Source: https://thespoon.tech/meet-three-startups-developing-growth-mediums-to-feed-cell-cultured-meat/#:~:text=Culture%20medium%20is%20one%20of,the%20only%20viable%20growth%20substrate.