Image rotating after uploading a doc with images

I assume that I observed an issue which is related to this ticket, but I’m not 100% sure. Beg your pardon, if I’m wrong.

I created this pptx file using the Community Edition Document Server v8.3.3.18 in my browser via the NextCloud integration. Then it was downloaded by a colleague, edited via Microsoft Powerpoint (he added the images) and uploaded to the NextCloud again.
Now the presentation looks like this in Only Office:

When I export the presentation as PDF file, I get:

Sample Presentation Image Bug.pdf (6.5 MB)

→ All the images are rotated. As a user I’d have expected to get the same as in the presentation.

Then I downloaded the pptx file and tried to open it on Manjaro Linux using Only Office Desktop Community-Version 9.3.0.140 (x64 deb). This doesn’t work at all (Error Message: Presentation can’t be opened.)