These app bypass your system take it seriously

Some applications intentionally bypass the system DNS configuration by using their own DNS-over-HTTPS/TLS resolvers, VPN-style networking, or embedded resolver logic. In those cases, the app is no longer relying on the OS-configured DNS provider, so services like NextDNS may not see or filter that traffic.

That’s not necessarily a bug in NextDNS, it’s more a reflection of how the application itself was designed. If you want strict enforcement, that usually has to happen at the router/firewall/network level rather than relying solely on endpoint DNS settings.