So the regression was introduced as part of XWIKI-23025 and more specifically in https://github.com/xwiki/xwiki-platform/commit/464ab58e48e5861b3398b93aad9baea5d22f924a#diff-b0490610e6476b15323d91aa5b1f8b90d763b6aad9bb8240e3f72a40ff925871. My understanding is that the change has been made on purpose: the label "title" is still available for screen readers but not displayed in the UI, and it's consistent with what we have with the inplace editor. Note that even in 17.5.0 and previous versions the inplace editor wasn't displaying a label for the title input.
So all in all I'm not sure it's an actual regression, we need to decide what we want to do here and maybe Thiago Krieck would have an input?
