I had something almost identical to this happen to me on Friday. Last year our company moved to a super locked down version of Teams, to the point where I couldn’t even open images that people put in the chat because of security issues, instead the image they posted would be replaced with an error image saying that I wasn’t allowed to open images, blah blah blah. That problem was resolved a long time ago though.

On Friday I was trying to send an image of some data processing to a colleague, and every time I put it in Teams, it would show up as that stupid error message. I spent a solid hour trying to figure out why that problem was back, was my computer not authenticating with MS properly, etc. Turns out my file browser was sorting by time order instead of reverse time order, and the screenshot at the top of the list from May 2 2024, was a screenshot of the error message that I used to send to IT when they were investigating the problem.