I took a look at your diagnostic and ran a few tests. I believe the bulk of the data is just from Google Drive's metadata returns, which are actually fairly large, per object, compared to some other services (about 4-5KB per object). They have a lot of metadata they track.
It looks like you have close to 1000 folders in one of your Google Drive accounts, which means at least 2x that in metadata object returns when odrive does a full scan, just for the folder objects. Add in the file objects, and the total data returned can start to add up to tens of MB pretty quick.
We may be able to trim these returns down to reduce the object metadata payload significantly. I will look into it.