It was observed that Firefox appears to be replacing users’ Custom DNS-over-HTTPS (DoH) settings with Cloudflare after they toggle between Custom and Default modes.

This issue surfaced recently and was highlighted in a Reddit thread by u/No_Greed_No_Pain.

However, a Mozilla employee later replied, suggesting it is likely a bug.

The original post on Reddit included screenshots showing the Custom DoH configuration disappearing after switching to the Default and back. Replies also confirmed similar experiences. Several users noted the change started after recent updates.

I have attempted to reproduce the issue on my end, and sure enough, the fallback does occur. In the image below, you can view the custom DNS that I entered.

After I toggled back to Default, the custom DNS was entirely removed, and it was back to Cloudflare.

The response from the Mozilla employee indicates that the Custom DNS wasn’t changed while active, and others say it might just be a visual bug. A user who noticed the issue consequently filed Bug #2052678 on Bugzilla. It appears to be a regression due to the redesigned settings interface on the browser.

Custom DNS refers to a user-chosen DoH provider entered in Firefox’s privacy settings instead of the browser’s default options. Cloudflare is Mozilla’s primary ‘Default’ DoH resolver.

Firefox appears to be replacing the saved Custom provider with Cloudflare, but it’s unclear whether it’s just an issue with the Settings page displaying it that way.

You manually re-enter your custom DNS to restore it. The issue particularly affects people who need to temporarily disable strict DoH to access public Wi-Fi login pages.

Overall, this appears to be more of an unintended regression, not a deliberate change. Since a bug report has already been filed, users can expect a future Firefox update to resolve the issue. Do keep an eye out for the latest versions of Firefox.

In other Firefox news, it’s now ahead of Safari in market share, according to one tracker. We covered that here. If you missed the company’s roadmap and AMA about the future of the browser, you can read about that here.

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