Pgvector extension is either out of date or not set up on one of your databases. I have encountered this on a few installs a few months ago. It is very simple to resolve, You just need to update it.
enter the db container, psql as discourse (or whatever is your db owner) and then choose each database and run
ALTER EXTENSION vector UPDATE;
Ps: it seems as if your setup is a bit different, the above will only work if you have a separate data container.