is it really possible that a pg_dump of my 64GB akkoma database is only 7.1GB (with the compressed custom dump format (-Fc)) or is it incomplete for some reason?

WARNING:  database "akkoma" has a collation version mismatch
DETAIL:  The database was created using collation version 2.42, but the operating system provides version 2.43.
HINT:  Rebuild all objects in this database that use the default collation and run ALTER DATABASE akkoma REFRESH COLLATION VERSION, or build PostgreSQL with the right library version.