Just want to report I solved this issue doing the following.
I turned on Peer DNS on my WAN interface, ETH1.
Then in IP/DNS, I removed any static DNS entries I had and unchecked Allow Remote Requests.
In IP/DHCP Server/Networks, under my network 192.168.99.0/24, I added a Static DNS entry of 192.168.50.1 which is my remote Wireguard server router. Now all clients connected to this network get DNS resolution from the remote router, hence no DNS leaks and if the tunnel were to go down, it will reconnect using the dynamic DNS servers it gets from WAN, ETH1.
Note: this only works if you disable Allow Remote Requests in IP/DNS as stated above.