What you're essentially asking is "what happens if FurAffinity retroactively claims copyright of uploaded work by changing their terms of service," to which the answer is "no, because copyright does not work that way." If it did, then any publisher of anything in any form anywhere at any time could forcibly transfer copyright from anyone.
What you're essentially asking is "what happens if FurAffinity retroactively claims copyright of uploaded work by changing their terms of service," to which the answer is "no, because copyright does not work that way." If it did, then any publisher of anything in any form anywhere at any time could forcibly transfer copyright from anyone.
— Chipotle