other good topics include stuff you do in your life and stuff that interests you. (consider privacy first with those). this includes stuff you read, watch or listen to.
also if you’re interested in some topics on the forum, read those and then that’d give you stuff to reply to. if you’re not reading much on this forum, that could be worth considering and discussing. like if you think it’s bad, or boring, or you don’t know how to understand it, or you always forget to read it, or you’re super busy with something else … something would be going on.
if you read stuff and can’t think of anything to say, that is a different scenario which can be addressed. that’s a solvable problem. a start of a solution is to consider that if you understand something well you should be able to add to it and say more, or at least summarize it and check your understanding. and if you don’t understand it that well you could talk about a hard part or confusion, or ask a question. so there are ways to reply whether regardless of your level of understanding. you can also ask why stuff is interesting, useful or important if you don’t see the point, though just focusing on topics that interest you works too (if few topics interest you, then that would be a discussable issue, you’re probably missing something).
the stuff I said is all generic and applies to everyone.