Pihole doesn't block ads with VPN connected

It worked! thank you for the complete explanation!

Now one question comes into my mind…are there any disadvantages for using this custom DNS?

Do you know what a dns leak is?

Well, there is always the risk of snooping and DNS-injection and interception issues if you aren’t using encrypted DNS and/or in control of your upstream DNS providers, or if they are known for doing something nefarious. This decision to use your own must be made by you.

Yes. I do.

My home network runs its own DNS server that fetches all unknown or non-cached queries from an upstream provider that is encrypted. So yes, by the definition of dns leak, then yes I’m leaking. But it doesn’t matter because everything that is “leaking” is encrypted and going to a different DNS provider than either my isp or my vpn provider.