When I display forum.qt.io posts in elinks browser, then it shows me historical version of edited posts. Good example is that thread, where three top posts were edited and appear as 6 posts!

The thread that you linked does not contain ANY edited posts, as far as I can see. Do you mean quotes, rather than edits?

Please fix it. Thank you in advance!

The content layout is done by NodeBB, so all NodeBB-based forums would likely produce the same results. I'd suggest discussing this at https://community.nodebb.org/ and/or the ELinks project instead.

I only tried sth like w3m or lynx about a bit less than 30 years ago in university.