Facebook rebranding to Meta and their efforts to rule this word is an interesting one. I don't know how it'll play out long term, given Meta is such an incredibly generic word
Due to their power (and money), they may see it different. Either way, the registration date of your Meta domain, and the overall intention counts. If you own "Meta Grass dot com", and you're a local grass cutter, or "Meta Fishing dot com", a local fishery / fishing equipment provider, I don't see Facebook picking up the phone to their lawyers to do something about it (maybe they would, maybe they are that ruthless, but really?). In summary: Don't step on their toes
IMO