I have a FP4 on Orange FR, and thus only got the recent, latest update, which also updated my phone from A12 to A13 (Orange had blocked the initial Fairphone A13 update).
No problems so far, but I’ve never tried changing OS, and I’ve never had any issues with 5G either (which is quite present around here, even though my house is in the boonies).
Overall I would say “good update” (although I might still regret saying this…), but your own mileage might vary greatly…
It all boils down to “Do you feel lucky?..” 