Using New Outlook on Windows for personal email, calendar, and contact management
We've seen this issue this morning, Microsoft have posted on their health page about it: https://admin.microsoft.com/Adminportal/Home/servicehealth/:/alerts/EX1015106
As a workaround, we've found that the old version of outlook is not affected and you can access images and download them fine through that, so as a workaround, we are migrating certain users back to old outlook as a workaround.
Doesn't bode well for new outlook tbh!