This can be reverted via secret settings https://firefox-source-docs.mozilla.org/mobile/android/fenix/Secret-settings-debug-menu-instructions.html

Hi

Please appreciate that the Nightly build is very much still under development and testing and may see changes that are incomplete.

You may with to try the Beta or Release versions of Firefox for Android which offer a greater degree of stability.

Maybe asking here for nightly support was not a good idea. However providing feedback for Release versions has too small impact, since its features are no longer subject to change, usually.