AdGuard is a Russian company, with Russian engineers, the majority of AdGuard developers and other employees working from Moscow, registered in Cyprus. Not a great recipe. Hard pass on security grounds.
MacPaw lists Russian-developed software as a risk because the government can access your data at any time — this is self-hosted open-source software though.
The FSB can’t just access your local server with an arbitrary court order.
Therefore this doesn’t feel like a legitimate concern but more like Russophobia, which I understand but also think is utterly unasked for as I know first hand how much Russian developers are suffering from the stupidity of their government.