Upload limit (sorry again) only for IOS app?

Hi all.

I would first like to thank everyone for their fantastic work, Nextcloud and the app have become great!!
But now sorry my problem, I installed a new Openmediavault server for us at home and installed NGinx Proxy Manager and Nextcloud in Docker containers among other containers. Works great except for the upload function from the smartphone in the IOS app. The last days I have searched a lot and tried all possible solutions in php.ini, nextcloud.ini, in my Docker-compose file or in the .htaccess file, but without success. In the PHP information in Nextcloud I see under Administration → System at PHP 1024MB at Memory_Limit and Max_Upload_size.
But the strange thing is that even if there are the default values with 512 MB, I can upload a movie with 582MB in the browser from my Macbook and from my iPhone (Safari and Brave) without problem.
But the other way around, even if it says 1024 MB at PHP info, I can’t upload the same movie via the IOS app, neither manually via the plus sign nor via the automatic upload, it always comes up with the error message “413 file too big” exactly when the upload of 582 MB is finished.

What does the app do differently than a browser on the same iPhone? So I am a bit at a loss currently what I can do additionally?

Best regards

Versions: OMV 6.8.0-1, NPM 2.10.4, Nextcloud 27.0.2, PHP 8.2.9, IOS app

Version: 8.2.9
Speicherlimit: 1,1 GB
Maximale Ausführungszeit: 3600
Maximale Größe zum Hochladen: 1,1 GB