James Wilcox () from Mozilla change with parameter implementation and settings , allowing you to control access to the about:config page in (a variant of the Firefox engine for the Android platform). The setting will allow developers of embeddable browsers for mobile devices using the GeckoView-based engine to disable access to about:config by default, if necessary, and return the ability for users to use it.
Ability to disable access to about:config to the codebase of the Firefox 71 release, which is slated for release on December 3rd. Question under consideration about:config by default in some variants of the Fenix ββmobile browser (Firefox Preview), which continues the development of Firefox for Android. However, to control access to about:config in Fenix setting aboutConfigEnabled to return about:config if necessary.
As a reason for wanting to restrict access to about:config, the situation is mentioned when in Fennec (the old Firefox for Android), inaccurate changes to about:config could easily bring the browser to an inoperable state. In the opinion of the initiator of the change, users should not be given access to insecure methods of changing parameters of the Gecko engine. It was also suggested as options to block dangerous settings by introducing a whitelist of settings that can be changed or adding a new "about:features" section to control the inclusion of experimental features.
Source: opennet.ru