Hi, From time to time we see posts from new users trying to use lookup field in formula. And I remember my first time issue with that when I just learned to use Airtable . Of course, info about lookup field behavior in formula can be found by search, but when you encounter this problem, it's hard to detect that problem related to field type.
Yesterday, when I tried to create a formula against Attachment field, using its URL, I saw the warning - that due to 08 Nov 2022 file storage policy changes, my formula may be malfunctional after some time, with a link to support article and checkbox 'Don't show again' . Maybe it should be implemented for a lookup fields as well? For experienced users, seeing warning once and check 'Don't show again' is not a big problem.