Private DNS on Android bypass Nextdns

I have a USG ubiquiti on my network. I made a vlan with Nextdns for parental control, and it works fine on PCs, but on Android phones I see no way to block when "Private DNS" is active in the connection settings. When I deactivate it, the block works like on PCs.

Is there a way to configure Ubiquiti so that phones cannot use "PRIVATE DNS"? I have configured the USG firewall so that they can only use Nextdns DNS servers and block other servers like 8.8.8.8, 1.1.1.1, etc.

Any ideas?

Thanks.