I think I’ve found the issue. It might be connected with the Private reverse DNS resolvers. By default the list of reverse DNS servers is empty, and I believe the checkbox to use this feature is also enabled by default. And since the list is empty it will use the IPS provided DNS servers, and will try to ask about my local IPs all the time, therefore creating huge artificial traffic in the statistics.
I put there IP address of the router itself and I will monitor if the top upstream DNS servers will change after some time. Thanks