It's all a bit weird so let's just disable it for now. For instance,
this is exposed as "text" font / colour but only affects the header.
Also, no other headers are cusotmisable in similar components.
Maybe closes https://github.com/ppy/osu/issues/31972. Not sure. I have
no reproduction scenario to work with, no solid understanding of how
the issue can happen, and if this doesn't fix it, then I'm not even
entirely sure how this can ever be fixed client-side.
The working theory is that not watching updates to the room provoked a
situation wherein the room was temporarily not in a correct state when
`WatchingUsers` changed, therefore the collection change callback failed
to exclude other players in the room from display.
I'm only PRing this because of the `next-release` tag on the issue.