Cert error when trying to access torrent trackers, causing problems with Jackett

Coming back to that, now that we have pinpointed the culprit.
It is possible that your PC is using other nameservers, without any configuration from your part. For example browsers now support DNS over HTTPS. Or at some point you added some additional nameserver, like GoogleDNS.
The fact of the matter is that your ISP seems to be blocking on DNS level certain sites. You could try to resolve other torrent or possibly banned hostnames to verify that using your ISP router as the resolver.