Firefox used DNS over HTTPS to bypass my operating system's DNS settings and ignore my local DNS infrastructure. In a network using split-horizon DNS, this caused internal traffic to use the external/public IP address instead of the intended LAN address.
Browsers should respect the operating system's DNS configuration by default, or make it much more obvious when they choose not to.
Here's an example.
Microsoft Edge currently offers a "Use current service provider" option for secure DNS, which respects existing operating system and network DNS configurations. I believe Firefox should offer similar behavior by default.
