Upgrades without `ALTER EXTENSION timescaledb UPDATE`

We have a custom-built postgres container image that also includes the latest version of timescaledb.

What happens if we swap the library version inside the image with a newer one without keeping prior versions and restart the cluster with the new image?

This way the older version will no longer be available, thus ALTER EXTENSION timescaledb UPDATE does not look possible. Does the extension handle this case, e.g. recognizes that it’s a newer version and does the update process unconditionally, or do we end up in a broken state where we are running the new version but with a possibly incompatible underlying structure?