I am connecting to sshd socket, listening on 22001. but in sshd config, theres no mention of that port. only 22

root@target-host:/etc/ssh# lsof -i :22001
COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
sshd    1973 root    3u  IPv4  19383      0t0  TCP *:22001 (LISTEN)
sshd    1973 root    4u  IPv6  19385      0t0  TCP *:22001 (LISTEN)

root@target-host:/etc/ssh# fuser 22001/tcp
22001/tcp:            1973

root@target-host:/etc/ssh# ps aux | grep 1973
root      1973  0.0  0.1  65524  5952 ?        Ss   03:04   0:00 /usr/sbin/sshd -D

made docker port for all running container. none of them has that one mapped

root@target-host:/etc/ssh# netstat -nlpt | grep 22
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1112/sshd
tcp        0      0 0.0.0.0:22001           0.0.0.0:*               LISTEN      1973/sshd
tcp6       0      0 :::22                   :::*                    LISTEN      1112/sshd
tcp6       0      0 :::22001                :::*                    LISTEN      1973/sshd

root@gitlab-runner:/# telnet 10.10.9.145 22
Trying 10.10.9.145...
Connected to 10.10.9.145.
Escape character is '^]'.
SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
^]
telnet> q
Connection closed.
root@gitlab-runner:/# telnet 10.10.9.145 22001
Trying 10.10.9.145...
Connected to 10.10.9.145.
Escape character is '^]'.
SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1
^]
telnet> q
Connection closed.

question: WTF??