standby server is complaining about missing wal file after switchover

Hi,
My postgres version is 14.2
I have setup streaming replication between a primary and a standby using
replication slot and without archive.
I have created replication slot "slot1" on the primary.
I did switchover following below steps.
1. shutdown the primary server.
2. created replicated slot "slot1" on standby and promoted it to primary.
3. run pg_rewind on the old primary and made it standby.
4. started the old primary as new standby.

I got following error in the new standby. it is complaining about missing
wal file on the new primary.

2022-10-13 12:58:48.497 UTC [25] LOG: fetching timeline history file for
timeline 2 from primary server
2022-10-13 12:58:48.508 UTC [25] LOG: started streaming WAL from primary
at 0/B000000 on timeline 1
2022-10-13 12:58:48.508 UTC [25] FATAL: could not receive data from WAL
stream: ERROR: requested WAL segment 00000002000000000000000B has already
been removed
2022-10-13 12:58:48.509 UTC [21] LOG: new target timeline is 2
2022-10-13 12:58:48.580 UTC [28] LOG: started streaming WAL from primary
at 0/B000000 on timeline 2
2022-10-13 12:58:48.580 UTC [28] FATAL: could not receive data from WAL
stream: ERROR: requested WAL segment 00000002000000000000000B has already
been removed

why the new primary has removed the wal file even though i created
replication slot on it before promoting.
value of max_slot_wal_keep_size is -1 and wal_keep_size is 0

Thanks,
Dhirendra.