Did the upgrade after first checking XDA and the web whether the update leads to any problems.
The update went through to the point of having to reboot my device. At this point however it would not boot again. It shows up as Quectel QDLoader 9008 at this point.
Update 30.04.2024:
Have to send my device in for repair out of warrenty. Fairphone does not have a repairtool and releasing mbn files needed to fix my device on my own woul be in breach of contract with Qualcomm. Most mbn files are leak files.