The Help Center article "How do I search?" on Meta SE has been updated after the bookmarks -> saves change to mention the in:saves operator in place of the inbookmarks:mine operator. But the update is not made on the corresponding article on Mathematics SE.
I haven't checked any other Help Center articles. Just mentioning this here as a post-it note (and also because I think it might be of interest to you, @MartinSleziak). Since we let our room on the Meta SE chatserver freeze, I thought this was the next best option to post such a message that doesn't quite fit into any of the other rooms.
@TheAmplitwist IIRC, it is possible to "push" changes to help-center to all sites, but only to those parts which use the default version - i.e., when there are no site-specific edits.
In any case, we're probably mostly interested for fixing that on Mathematics - for which we could ask the moderators.
On MathOverflow the help center says: "in:saves returns posts that you have saved". So it seems that on that it was fixed. (Probably no site-specific edits - so the default template was used.)