Probably some tab. Buggy javascript sometimes goes into infinite loops, including DDoSing its own website with 0-timeout requests, and no way to immediately tell other than the phone getting warm. You probably can’t see it now that the tab is closed, and I’m not sure if the mobile firefox has access to these features, but on desktop you can see open sockets with sent/received bytes in about:networking, and per-tab/per-addon cpu usage in about:performance, and set up logging for next time. But otherwise there isn’t a convenient chart with per-website data usage hidden somewhere.
Check out one of the privacy-focused Firefox forks like LibreWolf, IceCat, or Waterfox. All three disable/rip out pocket by default, I believe, and reduce number of situations they phone home to Mozilla or Google. Memory savings are minimal though.
Firefox on Android suddenly ate 10GB of mobile data, can I find out how? (fedia.io) en
Just wondering if I can somehow track if all that data was used by a particular add-on or tab or what....
Is preview on hover possible in firefox? (fedia.io) en
In Brave I can see a preview of the page by hovering over the tab. Is something like this possible in firefox? Add-on or from settings?
Optimized version of Firefox? (fedia.io) en
Is there an optimized version of Firefox that removed Pocket and other unneeded features? Does it use less memory?