[Bug] Maximum compatibility mode removes HDR information from JPEG photos in some cases

Steps to reproduce

• iOS camera settings set to "maximum compatibility" (saves photos as JPEG)
• Nextcloud Settings -> Additional settings -> maximum compatibility enabled ("saves images as jpeg if possible")

1. Take a photo (e.g. a photo of lightbulb (to maximize the HDR effect))
2. Go to the Nextcloud app and upload the photo to your Nextcloud (or let it upload via auto upload function) => file 1
3. Switch to the iOS Photos app, select the photo and share it to Nextcloud (and upload it) => file 2
4. Compare both files in your nextcloud => different file size, HDR is missing in file 1
5. Now turn off Nextcloud maximum compatibility feature and repeat step 2-4. Both files are equal now

Expected behaviour

Both files should be the same size. Nextcloud's maximum compatibility should leave JPEG files unchanged.

Actual behaviour

1 photo, 2 files, 2 sizes and the auto-uploaded one is missing HDR information.

Environment data

iOS version: iOS 26.2

Nextcloud iOS app version: 33.0.2.1 (c) 2026

Server operating system:

Web server: Apache, nginx

Database: PostgreSQL 15.16

PHP version: 8.3.30

Nextcloud version: 31.0.14

Start by reproducing the issue in the Nextcloud iOS app with Maximum compatibility enabled, comparing an auto-uploaded JPEG with the same photo shared from the iOS Photos app. Trace the maximum-compatibility JPEG handling used by the upload flow and verify that an existing JPEG retains its HDR information and matches the shared file in size and contents.