@hansw I certainly havent ruled out something in the QOTO domain, since it works uploading it to M.S it seems likely it is something specific to QOTO. I'm just trying to narrow down the symptoms so i can speculate on what it is and dive deeper.. can you answer the following questions

1) does this happen with all photos or just some?

2) does the issue occur when uploaded direct as a post, not to a group

3) are you using any client software?

4) can you send me the original file, attached to an email maybe, so i can try testing with thtat. I suspect the one I fetched was preprocessed and thus changed whatever property of the file triggers the error

5) what is teh file extension?