About 20 GB a month because I don't have Wi-Fi, so I have to do everything on mobile data. I used to use less than 2 GB half a year ago (in the same situation) and it has gone up over the months as I do more things on my mobile data.
When they killed support in October. I'm still using it at the moment. I need to look for a long term use Linux distro, get a flash drive to put it on, and get a new SSD. With the current prices of PC parts, it looks like that's not happening sometime soon.
I use Prism File Explorer. It's more advanced, has built in viewers for various file types, and lets you browse the root directory without rooting your phone.
Does it still convert if you upload in its formats (AV1 & Opus)?