This is not really a bug but IMO an inconsistency

Following inconsistency in usage with .mw-page-title-separator:

.ext-discussiontools-visualenhancements_pageframe-enabled .mw-page-title-separator {
    margin-right: 0.25em
}

Pages, which are not discussion pages, do not use this margin-right of 0.25 em.

That's why we have inconsistent page title names with this margin showing in pagetitles between namespace and page name:

Example:
https://de.wikipedia.org/wiki/Wikipedia:Bots (without margin-right), https://de.wikipedia.org/wiki/Wikipedia:Bots/Anfragen (with margin-right as discussion page) und https://de.wikipedia.org/wiki/Wikipedia:Bots/Anfragen/Intro (without margin-right)

Discussion pages have this margin-right, other pages haven't. This looks like an inconsistency and should be made consistent. This exists not in German language wiki project only but also in English language wikipedia and maybe several more.

Proposal of a solution: delete this margin-right style or set the margin-right style to all the namespaces > 0