My thought on this. About 2-3 years ago I sold a lot of items on FB Marketplace, I would get a ton of hits and interest almost instantly.
Now they are making you pay for views, you can sell something for free, but it will get very little views.
I have been sharing to groups also.
I paid for a $3 ad, and it generated little to no traction.
I have been getting much more traction on OfferUP, and not dealing with FB at all.