@mjosenhans Hi it's not so much the app but the OS that you need to change. >System Settings > Updates > Update settings (bottom of list)> Channels > change from "Dev" to "Release candidate" This will prompt the download of a new image approx 500mb (check you data-plan or go WiFi!) Once downloaded click on install.
phone will reboot and install.

Don't forget to backup any important data, (but everything should be ok...anyway... but just saying!!)

So you are changing your OS ubuntu (oversimplification I think!!) image to the Release Candidate that still works with Dekko and the camera etc.. and is the most stable at present.

This is temp fix until Dev is updated from what I understand.
Good luck
Alex

@dobey Thanks for the info.
The FP3 uses the "generic" android9 arm64 rootfs (https://ci.ubports.com/job/xenial-hybris-android9-rootfs-arm64/).
I just created a new system.img from it and now camera is working again.
Until yesterday I only did OTA-updates. Perhaps it was needed to do a full system update, to solve the issue.