Just an experience I just made using the “Service Menu” that provides hardware tests for the Fairphone 3 (and Fairphone 3+): When you choose Customization Setting → Reset Customization → OK, this will trigger a factory reset.
Fortunately, this was no big deal for me as I tried this on our local aachen.fairphone.community FP3 in near-vanilla state, and my own daily driver FP3+ runs /e/OS (so the Service Menu is not available on it anyway). However, I thought others might appreciate to know what’s actually behind that “Customization” button without trying it out themselves … 