Contact photos from iOS Contacts don't display in Signal (with workaround)

• [ x] I have searched open and closed issues for duplicates
• [ x] I am submitting a bug report for existing functionality that does not work as intended
• [ x] This isn't a feature request or a discussion topic

Bug description

Contact photos from my iOS address book (iCloud) aren't showing up in Signal, even though "Use Contact Photos" is enabled and Signal has full access to Contacts. The contacts themselves resolve fine — name, number, everything — just no photo.

Looking at these two of the debug log:

WRN [OWSImageSource:130 imageMetadata]: Image does not have valid format. ERR [OWSContactsManager:695 systemContactOrSyncedImageData]: Couldn't validate system contact avatar

I found a reliable workaround, if I take a screenshot of the contact's photo and assign the screenshot as their photo instead of the original photo file, it shows up in Signal every time. I tested this on several contacts and it worked for all of them.
My guess is this is related to the HDR "gain map" data that iPhone 15+ cameras can embed in HEIC/JPEG photos by default.

Steps to reproduce

• Assign a photo taken with the Camera app to a contact stored in iCloud, via the native iOS Contacts app
• Confirm the photo displays correctly in the Contacts app (list and detail view)
• Make sure the contact is also a Signal user, with no Signal profile photo set
• In Signal, enable "Use Contact Photos"
• Open the conversation with that contact in Signal

Actual result:
No contact photo appears in Signal.

Expected result:
Signal should display the iOS contact photo, as described by the setting.

Workaround found:
Take a screenshot of the original photo and assign the screenshot as the contact's photo instead of the original file. This has displayed correctly in Signal every time I've tried it, on multiple contacts.

Device info

Device: iPhone 15

iOS version: 26.6.1

Signal version: 8.25 (1809)

Link to debug log

https://debuglogs.org/ios/8.25.0/6d3c7ccfd0888afc02485df5ac3307c328563053c7134e5d6751ca9d47a5c2c1.zip

Thank you very much for the work, from France 🫶🏻

Start by inspecting OWSImageSource.imageMetadata and OWSContactsManager.systemContactOrSyncedImageData, which appear in the reported log, then reproduce with an iOS camera photo assigned to an iCloud contact and compare it with a screenshot. Done means Signal displays the original contact photo when Use Contact Photos is enabled, without requiring the workaround.