JPG File renamed to JFIF on download via Webinterface

A user reported a strange behavior when downloading JPG files from his Seafile Library via Browser. The file is shown as .JPG in the Browser. When downloading, it is renamed to JFIF. This happens only with his file. I wasn’t able to reproduce this effect with other JPG files.
We are using Seafile server community 9.0.10 on Ubuntu 20.04 with Apache in reverse proxy mode infront of it.
I asked the User if I can share his file here. Will comment with attachment if he allows it.

Maybe any had this issue and knows a workaround?

I got further information. The Problem does not happen if I upload the file via Browser. It seems to only happen if the file (a photo taken with an iPhone) was uploaded by the Seafile iOS app.
Will test this with my Apple specialist and report back here.