Using Classic Outlook on Windows for personal email, calendar, and contact management
I have the same issue with Outlook 365 enterprise at work. It seems to happen with any meeting appointment that contains a link, including Google addresses. We don't use Teams here, we have to use WebEx. I don't have to have locked my screen to get this message on any old appointment I want to open and simply check a detail quickly. If I open it, read and close it almost immediately, it closes fine if it contains no link, but always asks me to save changes if any kind of link is present in the entry, whether in location field or body text.