Traefik does not "forward" the local IP, but the connection to Adguard has Traefik IP just as origin, because that's where the local connection is coming from.
Traefik will "forward" IP information by placing them in the HTTP header ( X-Forwarded-*), I think that's done automatically, check if Adguard supports getting the IP from the header. Alternatively you can check if Adguard supports proxy-protocol.