Just to add my experience - I have updated my phone 2 days ago and have had no major issues so far.
The only thing that may have happened is that the phone now sometimes gets stuck on slow charging. However, as taking out the plug and reconnecting a few times usually fixes that, this is a small annoyance, rather than a big problem (also, there’s a chance that this was a coincidence, as it seems that FP3s sometimes randomly develop this issue - FP3 Slow Charging)
Edit: further two days later and the slow charging issue seems to have disappeared. So either it was wobble, unconnected to the upgrade, or it somehow sorted itself out.