Interesting. Why?
Considering that the so-called factory reset only wipes the data partition (mainly user data + Apps installed by the user and their data) and the cache partition … where does the firmware come into play?
And what kind of “firmware” are we talking about in this context? The OS? The modem firmware ZIP for Custom ROMs (not needed when using Fairphone OS or Fairphone Open OS)?
The factory reset touches neither the installed OS nor any firmware parts. If that limitation itself is suspected to be a problem, then a complete reinstall from scratch should be considered?