In 20.11 when you activate a Select2 pull down by tab+enter or clicking on it, the cursor is in the input field and you can type to select one of the entries. In master, I need to extra click in the search field. Tab+enter don't get you into the search form, I haven't found a way to do it with just keys yet.
Tested on the edit item form.
I was first to file, but Aleisha's report is the nicer one, so marking mine as duplicate. *** This bug has been marked as a duplicate of bug 31646 ***