So did someone edit the first post in the about topic and then other people started replying? That’s weird thing to do but things happen! I’d create a new topic and copy the OP text into it and then save it and change ownership to the relevant user. Then move all the replies into it. You’d lose the likes etc on the OP but not for the rest.
Then go back to the about topic and clean it up by deleting all the mentions of posts being moved, edit the text of the OP as you see fit and then close it so nobody tries to reply to it.