I've also noticed oddities in the map threads here. There's a problem with blue and grey (what others tell me is grey actually looks blue to me).
I don't have this problem on other sites, so I think my monitor should be okay.
I suppose it might have something to do with my Dark Mode settings that apply to most sites I visit. I had to do this to make it more comfortable to read everything. But the theme you designed has been working for me except for the badge colors. If anything else isn't working (someone mentioned link colors) it may be that I just didn't notice.
Please keep in mind that these issues don't make the forum unusable for me. I just find them bizarre. It's unsettling to see the way the various moderator and admin badges change. For instance, your own currently looks red to me. At other times it's looked pink and I kept wondering why you'd have pink ones.
As for images, the ones I post are done by using the attachment feature. I haven't had any problems there.