Sometime no startup with 'Failed to start Add random entropy from file' (9.2.6 RPi4)

1st Official Post

    Most times, it starts up without problems. But on some days I get

    [FAILED] Failed to start Add random entropy from file

    See 'systemctl status add-entropy.service' for details.

    The next is

    (1 of 2) A start job is running for Wait for Kernel Time Synchronized

    which takes >10 mins, then fails. After that, I get many [FAILED] jobs and in the end I get

    [!!!!!!] Failed to load rescue target.

    The crazy thing is, that on most days, it starts up without problems. But on some days, I get this error. Retry does not help. Unplugging it for an hour does not help. But next day, it works again.

    Any ideas?