What could cause this errore and how can i solve?

Your log looks Ok.

You router distributes your Pi-hole's IP as DNS server via DHCP (I guess together with your second Pi).

[✓] IPv4 address(es) bound to the eth0 interface:
    192.168.1.254/24

      dns-server: 192.168.1.254
      dns-server: 192.168.1.253

Your Pi-hole forwards the requests to your local unbound

    PIHOLE_DNS_1=127.0.0.1#5335

The question would be why your TV is sending queries to your router instead of Pi-hole? Does it use DHCP? Can you set a fixed DNS server at the device?

   Sep 21 09:49:23 dnsmasq[11709]: query[A] customerevents.netflix.com from 192.168.1.101
   Sep 21 09:49:23 dnsmasq[11709]: gravity blocked customerevents.netflix.com is 0.0.0.0
   Sep 21 09:49:23 dnsmasq[11709]: query[A] ichnaea.netflix.com from 192.168.1.101
   Sep 21 09:49:23 dnsmasq[11709]: gravity blocked ichnaea.netflix.com is 0.0.0.0
   Sep 21 09:49:23 dnsmasq[11709]: query[A] customerevents.netflix.com from 192.168.1.1
   Sep 21 09:49:23 dnsmasq[11709]: gravity blocked customerevents.netflix.com is 0.0.0.0
   Sep 21 09:49:23 dnsmasq[11709]: query[A] ichnaea.netflix.com from 192.168.1.1
   Sep 21 09:49:23 dnsmasq[11709]: gravity blocked ichnaea.netflix.com is 0.0.0.0

Just to see if the device stops the spamming, you could (temporarily) whilelist ichnaea.netflix.com

P.S. You have conditional forwarding enabled, but this should be no problem here.

    REV_SERVER=true
    REV_SERVER_CIDR=192.168.1.0/24
    REV_SERVER_TARGET=192.168.1.1
    REV_SERVER_DOMAIN=RT-AC86U