3650d is 10 years!
LTS mostly takes care of that already, so you really shouldn’t be worrying about storing all that data at short-term level.
I mean, why would you care what the weather was like 9 years, 5 months and 3 days ago?
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Thanks @ShadowFist, I did not know about the LTS-magic, keeping sensor data literally forever but only on hourly aggregated values. That is absolutely sufficient, even for the question you asked. 
So I changed configuration.yml from
recorder:
purge_keep_days: 3650
to
recorder:
purge_keep_days: 32
and restarted Home Assistant. Might take some time tomorrow morning, doing the LTS magic…
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So… as a wrap-up to mark as Solution:
If upgrades on a Homeassistant Yellow fail you need to do a full re-install of Homeassistant OS, using a USB stick with the Yellow Installer and following Reinstalling the operating system on CM4 – Home Assistant Yellow.
If you have an NVMe datadisk installed you need to wipe it manually connecting it to another computer and before the upgrade process. At least I did not manage to push the right blue/red buttons.