Copied from there:
Currently info pages such as https://www.mediawiki.org/w/index.php?title=Topic:Tuxqtxu1kp6n1m1q&action=info use the same displaytitle as the sort key. Aside from not reflecting reality, it makes searching for flow titles a mess, see topic%3A+contentmodel%3Aflow-board .
While searching for thread posts might never be possible, it would be at least useful to be able to search prior discussions by title. This only works with structureddiscussions boards but not threads, e.g. it is possible to find this board "Extension_talk:StructuredDiscussions" but not a thread like Topic:Ukzjwfa58ewp4zm6 without knowing the whole strange id.