iPhone photo sync stores JPG instead if HEIC - Can this be changed?

Hi everybody,

I could not find it in the searches, so I open this topic.
My plan was to use Seafile to backup all my photos from an iPhone via wifi to my server (My Cloud Home with Debian).
In a first test I tried uploading all photos from an iPhone.
It seems that all HEIC photos are converted to JPG by the app. I could not find the option to stop this.
Is there any way to switch this off? Or will HEIC support be added to the app in the (very) near future?

Can someone confirm that this really can’t be changed?