Firefox large background data usage

Hi! This morning I woke up to a warning that I had exceeded my data usage for the month (which is weird since I've been laid off since March and rarely leave the house). I checked my mobile data usage stats, and at 7:45 am (before I woke up) my phone downloaded 300mb. It's not a ton I know, but I still have a 500mb plan as I mostly listen to stuff I download at home, and no idea how or why firefox would independently decide to download a large... something... without being instructed. The only app that has over 100mb usage in the last month on my phone is Firefox. Google play store has everything marked as download over wifi only. Firefox v 68.10.1 Android v 6.0.1 Phone is ZTE B2017G Any help is appreciated! Thanks in advance.