[stupidthrottle]

> It would be nice if these apps could detect whether the system is using DoH and only fall back to their own DoH resolver in the case they're using "legacy" DNS.

In which case these applications are either broken or malware.

The application needs to fix that by using DNS supplied by the OS, as everyone should do.

[zaarn]

There are plenty of reasons to use a different resolve on app vs OS level, not only for malware or "broken" applications.

The DNS setting by the OS, just like the proxy settings, is a first suggestion on how to connect.

Chrome will contact 8.8.8.8 in certain circumstances and Firefox has DoH. Both can set proxy settings different from system via various means.