I have configured my macOS Catalina to use 1.1.1.1 as DNS Server address. I have also enabled chrome://flags/#dns-over-https flag.
When I visit https://1.1.1.1/help, The page shows that My browser is not using neither 1.1.1.1 nor DoH: https://1.1.1.1/help#eyJpc0NmIjoiTm8iLCJpc0RvdCI6Ik5vIiwiaXNEb2giOiJObyIsInJlc29sdmVySXAtMS4xLjEuMSI6IlllcyIsInJlc29sdmVySXAtMS4wLjAuMSI6IlllcyIsInJlc29sdmVySXAtMjYwNjo0NzAwOjQ3MDA6OjExMTEiOiJObyIsInJlc29sdmVySXAtMjYwNjo0NzAwOjQ3MDA6OjEwMDEiOiJObyIsImRhdGFjZW50ZXJMb2NhdGlvbiI6IllZWiIsImlzV2FycCI6Ik5vIiwiaXNwTmFtZSI6IkNsb3VkZmxhcmUiLCJpc3BBc24iOiIxMzMzNSJ9
It used to work intermittently few weeks ago.