Libraries are reporting a change to the way you can use the TAB button in the item editor. Prior to 21.05, you could use the TAB key to move through the item editor, hit tab and it would confirm the highlighted/upper choice and go to the next field. You can't just tab to Not For Loan, hit O (for Ordered), and hit tab to select that and jump to collection code. You now have to click and/or use enter.
I think this is a duplicate of Bug 28903. If I misunderstand, please reopen. *** This bug has been marked as a duplicate of bug 28903 ***