Well, I believe you can not worry.
situation same to me for a looooong time:
https://community.glideapps.com/t/too-much-google-sync/56354/67
I have a starter plan. still not understand what that sync from and why. looks like in usage - wrong information or ghost of sync that not really exist. so, extra sync in usage don’t affect to all usage. i’m sure you can approve it when all usage become more than total you can have in month.
it’s really nervous each month, get alarm about “approaching the limits”, but this is the Way.