Probably, connecting the dots was never his forte.

There are different kinds of tests, but this is an example: https://www.healthcare.uiowa.edu/familymedicine/fpinfo/Docs/MOCA/MoCA-8.1-English-Test-2020.pdf

Skewed telemetry probably, as most users that are aware you can move the taskbar are also aware you can just disable the phone home crap and will therefore not show up in the statistics.

Yeah, that’s definitely a concern. My first installation shredded its SD card in no time due to each request getting logged and stored on disk. Turning off long term query logging mitigated that issue, for my home network I don’t care about that history anyway.

Anybody got the feeling some games may be negatively affected by a PiHole ?

My RPi 2 has been happily running PiHole in my network for about 8 years now and with a number of pretty strict block lists, personally I never had any issues with games.