Why would enabling or disabling AdGuard for Android change my public IP?

Since I just set up a VPN to my home server, I performed various tests and I found that, when I'm on cellular data, enabling or disabling AdGuard for Android (paid version) changes the IP detected by whatismyip.com or ipleak.net. Since I'm on mobile, neither one obviously matches my home IP. Today with AdGuard, for example, I could get 77.63.3.x which belongs to KPN, my provider, and an IPv6 address as well. Without AdGuard my IP is 77.63.6.x, again from KPN, but located in Utrecht. Another day the difference was "bigger", not even the first byte of the IPv4 matched. AdGuard is set to use a local VPN, since my Android is not rooted.