In its most general sense, a fair use is any copying of copyrighted material done for a limited and “transformative” purpose, such as to comment upon, criticize, or parody a copyrighted work. Such uses can be done without permission from the copyright owner. In other words, fair use is a defense against a claim of copyright infringement. If your use qualifies as a fair use, then it would not be considered an infringement.
https://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/
RE: When some witnesses and others give their voice / upvote to an account that uses a photo for another person and even his name "Justin Sun"