table lookup for pg_stat_progress_vacuum doesn't work

Hello !
We want to lookup the table name for entries we see in pg_stat_progress_vacuum.
When we do this based on relid from pg_stat_progress_vacuum we don't find an entry in the pg_class table (no match where pg_stat_progress_vacuum.relid=pg_class.oid).
Should that happen at all and where can I do the lookup if not in pg_class ?

Here is one example how it looks like:
select relid::regclass as tablename, relid from pg_stat_progress_vacuum

tablename relid
449463 449463 No tablename, no entry in pg_class for this id
pg_largeobject 2613 That's how it should look like.

Best regards
Uwe