I'm not very versed in copyright and I'm wondering what I do if I don't know the copyright information on an image.
Topic on User talk:Ethar
it's mostly about giving attributions to the right authors, i recommend reading this instead https://www.uzh.ch/blog/ub/2023/05/24/creative-commons-licenses-in-a-nutshell/?lang=en. I wouldn't consider social media photos as creative commons unless they were clearly stated but to play it safe, i'd just mark it as CC BY-SA 4.0 and give attribution.