You posted this in Community Help with the tag "unsupported OS." But, you are running Pi-hole in Docker, and the OS in the container is supported. I removed the tag from the post.
You have Pi-hole configured for the eth0 interface of the Docker container, but how is this interface visible to other clients on the network? The listed IP is contained within the Docker container, and unless you set up access to the rest of the LAN, they don't see it.
[i] Default IPv4 gateway(s):
172.17.0.1
* Pinging first gateway 172.17.0.1...
[✓] Gateway responded.
[i] Default IPv6 gateway(s):
*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] www.relacjetychmotywacja.lat is 0.0.0.0 on lo (127.0.0.1)
[✓] www.relacjetychmotywacja.lat is 0.0.0.0 on eth0 (172.17.0.2)
[✓] doubleclick.com is 172.253.116.139 via a remote, public DNS server (8.8.8.8)