After DB upgrade from PG13 to PG15 showing error

Dear Team,

We have upgraded PostgreSQL DB from version 13 to 15 version .

We are facing issue in PG15 we not enable any parameter related to AUTOVACUUM , but still running on PG15 data base.

Below process showing :

2313192 | 02:10:01.283176         |            | myLava  | active | autovacuum: VACUUM ANALYZE public.tstock_movement (to prevent wraparound)

And one more issue we are facing after upgrade lot of alert is coming in DB log file , please suggest this is bug in Postgresql-15 version.

2024-08-26 00:00:36.783 IST [702937] WARNING:  oldest xmin is far in the past

2024-08-26 00:00:36.783 IST [702937] HINT:  Close open transactions soon to avoid wraparound problems.

        You might also need to commit or roll back old prepared transactions, or drop stale replication slots.

2024-08-26 00:00:36.784 IST [702937] WARNING:  oldest xmin is far in the past

2024-08-26 00:00:36.784 IST [702937] HINT:  Close open transactions soon to avoid wraparound problems.

        You might also need to commit or roll back old prepared transactions, or drop stale replication slots.

DB  OS -RHEL8.