DNG images from iPhone downsized

Nextcloud version: 16.0.1
Operating system and version: ASUSTOR 3.5.2
iPhone app version: 3.0.13

Hello,
whenever I shoot RAW with my iPhone (I’m currently using Halide app), the pictures sent to my Nextcloud installation via background upload are saved in a downsized quality: a RAW picture on the iPhone XS is usually around 11MB and it is saved as a 3/4MB picture on the server. Opening it in an editing software reveals that the photo is low quality, as if it was a jpeg which has been renamed into dng.
Is there something I can do about this? Is there some kind of setting I need to enable in order to get my DNG images saved correctly on the server?
Thank you

EDIT: the image uploaded by Nextcloud iOS app is actually a JPEG renamed in DNG