Necessary actions after an OS upgrade

We use Crunchy Postgres for Kubernetes (CPK). With CPK 5.8, there will be an OS upgrade from UBI8 to UBI9 images. As described in both the Crunchy and Postgres documentation, conflicts due to collation version mismatches following an OS upgrade can lead to incorrect queries.

https://access.crunchydata.com/documentation/postgres-operator/latest/tutorials/cluster-management/update-cluster#changing-base-images
https://www.postgresql.org/docs/current/sql-altercollation.html#SQL-ALTERCOLLATION-NOTES

According to the documentation, we plan to perform a "reindex database" and a "alter database refresh collation version" immediately after the upgrade.

Is there anything else to consider? I'm wondering if this is sufficient.

What about materialized views, (text) function-based indexes, and extensions? Couldn't problems arise here as well? None of the documentation addresses this. Am I thinking about this incorrectly?

Ideally, I would like to have a precise list of everything that needs to be considered and done afterwards.

Thanks, Markus