Do you still the have the link to news article where it was reported?
Earlier I was using Pi-Hole on my network then switched to AdGuard Home (not same as AdGuard DNS) as it is an open source product with in-built DOH support (yes, I can setup Pi-Hole to do the same, but that’s an extra manual configuration) and Privacy Guide seems to recommend it over Pi-hole. After reading your post, I tried to lookup more about it. Nothing on Wiki. Closest thing is this. If the allegations are true then I need to switch back to Pi-Hole.