LuCI system log is clogged with 'unknown host' after `config dnsmasq` is listed with (ad) Web addresses

My router is a TP-Link c7 running on a release 19.07.8 custom image.

In my LuCI System Log, I get many lines that look like

Sat Oct 23 14:33:54 2021 auth.err sshd[9040]: error: connect_to no-thanks.invalid: unknown host (Name does not resolve)

As background, I have listed Web addresses in the config dnsmasq block of /etc/config/dhcp, as a means of blocking access to those Web addresses (ads). See this earlier post:

How to block particular Web sites

I should also add that I often use this router as a SOCKS proxy for Web access. From the router's perspective, it handles traffic to and from both LAN and me logging into the router's OpenSSH server from WAN. (I don't know that this makes a difference.)

Questions.

  1. Could the config dnsmasq listing be the cause of System Log 'unknown host' lines? (Otherwise I have not experienced any failure to resolve.)

  2. Is there a way to suppress the 'unknown host' lines from the System Log (so it does not get clogged)?

  3. Is there any reason not to suppress those lines? If there is a name resolution failure, wouldn't the (human) user know it without having to look at any log?