After installing Firefox for android I noticed that webpages were appearing very washed out, colours faded, blacks rendered as grey etc. It seems similar to this issue https://support.mozilla.org/en-US/questions/1329680 Trying the resolution there I noticed that about:config just loads as a blank page. The issue is dependent on the theme active when tab was created. For example if the browser is in light theme and a tab is created, then you change to dark mode, pages will continue to render vibrant until a new tab is created. Conversely changing to light mode pages will remain faded until a new tab is created. This behavior is also present if the Theme is set to follow OS if OS dark pages are faded, if OS light pages appear normal.