As my phone is encrypted, after each reboot it asked for my PIN before it even started to boot Android. Now it doesn't anymore - it boots directly to Android, asks for the two SIM PINs and then for the lock screen PIN. I did not change anything, the phone's status is still "Encrypted".

Oh, and the bootup sound is also gone.

Firmware is 20180307-1950. Was something changed with that firmware and I simply did not recognize it until today?

Edit:
Ok, there's a separate entry deep in the security settings to set a PIN that is required to boot. It seems that PIN was deleted for some reason. I set it up again and now it works. And the bootup sound is also back.

.... A little bug fixed by itself