It is not an issue with AdGuard. It is how their site is designed. As long as you are on their domain, you are good. I suppose you are trying to access the page from Russia/a Russian Proxy/VPN? It is perfectly safe to be on paypal.com/ru/home. The site is designed to take you to their local page based on the IP geolocation.
Thing is. I'm not in Russia. Strangely it is fixed. I'm back to using Adguard DNS and Adguard Safari Extension filter.
Strangely too another page I was visiting (but not logging) was Localbitcoins.net. If I changed the country (to look at offers) to let's say, Netherlands, it showed some menus in Russian.