The goal isn't to optimize images. Many websites use the webp format and it is impossible to embed this pictures in a post.
If XF cannot support this format it could be a solution to change the extension to JPG because than embed images can be shown in the posts.
Links from registered users have the nofollow tag. But if you use the unfurl link with preview the tag is missing for all usergroups and all external links are dofollow.
I think that's a bug and it should be solved.
Furthermore in my opinion it is not acceptable that staff external links are...
Eventually it is necessary to explain the forum rules clearer. No answer for a question means.....
1. No idea
2. I don't know
3. It isn't possible
4. It is possible but... (see 1.)
5. It's all the same to me