@oli.sax I asked regarding this in the "UBports Welcome & Install help [English]" Telegram channel back in April. Someone responded "oh crap i forgot to fix that". I did not follow up as it was not that important to me.
@Kutzi its nothing to worry about, if not all mounts work in recovery, but the relevant (userdata) should be mounted still.
Now just have a look at /data/backups ls -la /data/backups
@Zardozor25 Usually on Fairphone you might press and hold Power and - Vol- until bootloader appears, then select "Fastboot" mode (1rest option) with the Power button.
It's the beginning of the journey for the FP6 to reach some day the land of UT ️
https://gitlab.com/ubports/porting/reference-device-ports/halium-14/fairphone-6
Don't expect it to be sooner than later