Posting here as suggested in https://bugzilla.mozilla.org/show_bug.cgi?id=1915770 - If you vote here, kindly vote on bugzilla as well. Thank you!
I use the Quick Filter / Quick Search extensively.
In the past, pressing Enter after typing the search criteria would have no effect and the Quick-search would continue normally. Since a few versions ago, pressing Enter stops the quicksearch and takes the user to Global Search. In my case, that's never my intention - if it were, I would've pressed Ctrl-Shift-F in the first place. When I type things in the quick-filter field, I want to stay WITHIN the mailbox in which I'm doing the search and just have messages filtered, regardless of whether I press Enter.
Having used Thunderbird for years, muscle memory makes it very difficult to avoid this issue, so it would be great if this were a configurable setting.
Currently some kind soul created an add-on to get the old behavior back (see the discussion in bugzilla - link above), but it really should be a setting.
Thanks!