I'm not sure the delivery failure is related to the appearance change. Only ONE email address appears to have been impacted, but it happened at the same time, recipient reported no other such failures, & that makes me nervous. The message was from "Postmaster" & said: This is an automatically generated Delivery Status Notification. Delivery to the following recipients failed.
It is an IMAP account.
The icon itself doesn't bother me -- just want to make sure it's OK/is normal & does not indicate a problem. I just don't understand why the appearance of that ONE screen suddenly changed like that. I have Microsoft Office Home & Business 2019.
Found where it said Office updates were available & updated, but that icon is still there.