Did you try to join the French group here /e/OS community # Groups?
If your previous Android version was Android 10 (Q) then you are correct that encryption changes will prevent moving Android version forward without Format data.
Indeed. Many builds have rebuilt very recently reference
Good so what version is showing?
For clarity was /e/OS running ? Reboot system now is likely to consolidate the Upgrade.
Importantly what was the file you are updating / upgrading with ?
Advice will be guesswork if you cannot better define “a very deprecated version of /e/” 