HA hanging while upgrading from core-2021.11.3 to core-2021.11.4

Hi there, while trying to upgrade from core-2021.11.3 to core-2021.11.4 the HA becomes completely unresponsive - I can ping it but cannot i.e. ssh into it.
After 1h of waiting the only way to get back to life is hardware reset of Pi (power off/on) as HA does not connect from browser anymore.
My installation is HA OS on Raspberry Pi 4
Until this upgrade, all upgrades were always working fine
Any way of checking what blocks this upgrade or so?

Thank you
zyga