Doesn't block anything unless I use this app to change the DNS https://play.google.com/store/apps/details?id=com.burakgon.dnschanger
It's also at like the android settings don't actually do anything but that app forces the change. But I'm not entirely sure I want to use that app for sensitive data, I have no idea what it's actually doing.
My router is a sky hub so it won't let me change dns settings AFAIK so I have to do it on all devices. I can get it to work fine on Windows devices but not android.
Your Pi-Hole is working properly. The problem is likely that the Android phone has a separate DNS that it is using, allowing some or all of its traffic to bypass Pi-Hole. I would check some of the online forums for setting DNS on an Android phone.
I just changed both DNS 1 and DNS 2 to the pi hole address and it seems to be working for now, but I'll see how it goes. Previously I had pi hole as DNS 1 and DNS 2 was blank