High CPU usage

Hello,

I am using PostgreSQL v14.5 on Linux Debian 11.5. I recently observe very
high CPU usage on my Linux system as below

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+
COMMAND
2357756 postgres  20   0 2441032   2,3g      4 S 298,7  67,9   2114:58
Tspjzj2Z

I could not find any file named Tspjzj2Z on the file system. I could not
find PID number using below SQL

SELECT * FROM pg_stat_activity

I also see another suggestion like below to identify long running queries

SELECT max(now() - xact_start) FROM pg_stat_activity
                               WHERE state IN ('idle in transaction',
'active');

I get no long running query at all.

There is no replication of any kind. This is a single instance server which
alows certification login only.

I appreciate any help to figure this out.

Thanks & Regards,
Ertan