I’ve added 18.104.22.168, 22.214.171.124, 2606:4700:4700::1111, and 2606:4700:4700::1001 to my DNS settings in macOS system preferences per the instructions.
Everything works fine except for icloud.com, it will not load at all. As soon as I remove Cloudflare’s DNS servers, I can load the page. Same behavior in Chrome and Safari.
The funny thing is that the page loads on my phone when using the 126.96.36.199 app in both 188.8.131.52 mode and 184.108.40.206 with WARP+. But when I put the custom DNS addresses in my router settings, it again prevents loading icloud.com from my phone on wifi.