I believe this is due to the DNS name "pixellibrary.org" resolving to 126.96.36.199 (on port 80 and 443 for web servers), but only resolving to my server IP 188.8.131.52 with minecraft protocol on 25565 (due to SRV record). This is not an unknown server configuration, and it works 100%. Players can connect to pixellibrary.org with default port FINE, players can navigate to pixellibrary.org or https://www.pixellibrary.org, etc. totally FINE.
However, it seems https://minecraft-statistic.net/ and https://minecraft-server-list.com/ do not handle this well at all. They seem to ping the dns name to resolve the IP (which is where the problem is) then add the port to this and ping that. That will not work on my server. How can I deal with this? Is it possible to get this working? This is very disappointing for a huge server list website :((