getting warnings in alertlog after connecting with observer

DB environment: 19c dbs with latest patch (19.20) , with 2 standby ( HA and DR) , 2 observers (mater and backup ). all Linux servers.

Now, Without the observers, everything is working as expected.

But when I turn on the observers with fsfo enabled, getting below error which is updating in alert log for every 2 or 3 seconds. Except that error, everything else works fine.

WARNING: process USER (ospid: 3981573) was unable to attach SMR.

ORA-27300: OS system dependent operation:open failed with status: 2

ORA-27301: OS failure message: No such file or directory

ORA-27302: failure occurred at: sskgmsmr_7

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the process ospid=3981573

$ ps -ef|grep 3981573

bpo0003a 3981573    1 0 01:10 ?    00:00:01 oracleBPO0003A (LOCAL=NO)