Each of these indicates a failed or missing substitution - I haven’t read over all of the previous posts but I see a LOT of people on Docker version 20.10.5 are having trouble:
This might be a cause of the problem.
Did you take a backup of the server first? Can you revert back to before you first tried the upgrade?
If not, I’m sure all of the data is still there,
Regardless, take a backup of it now.
What do you see if you:
cat /var/discourse/shared/standalone/postgres_data/PG_VERSION