Apple Mail does not play nicely with Outlook/Exchange/M365 accounts. Everywhere I've worked had said "You can use Apple Mail if you want, but IT won't be supporting it. Outlook app only." Always issues with syncing mail or contacts.

Outlook is notoriously difficult to interface with. The only real success story I'd ever seen was some Thunderbird extension. I think it was called Owl. I had the company pay for it, but I think that it wasn't very expensive. It synced contacts and calendar too.