But if I see eg. cdn.adnxs.com Pi-holed, why do I see an advertisement. I also tried to add a domain to the blacklist, but I am still able to access that website.
Can you please run pihole -d? Once it asks you to, try and load tweakers.net and then upload the log and provide the upload token so that we can take a closer look, thanks!
Hmmm, could you try that again please and give it some time whilst loading the website before pressing ctrl+c on the script? It appears to have cut off that part of the log!