Using Outlook for Android for personal email and calendar management
I think there's something going on Microsoft's end right now. I am seeing many people reporting this issue, but Microsoft has not announced this on their service status page. However, there's an active service incident report on the commercial side. It can be related. You can use Microsoft's X/Twitter account page to check for update https://x.com/MSFT365Status/status/2094465993007378744