Many thanks to the team at Fairphone who developed FP3 Software update: 6.A.020.0.
I immediately noticed,
WPA3 + WPA2 mode works. No problem with reconnecting after reboot or manual disconnect.
Device boots faster.
Delayed SIM PIN is not fixed yet, but I believe it will be in the future.
I will need more time to evaluate the rest of problems I’ve reported earlier.