Restored iMac Still Downloading files from iCloud

I did a software update and it crashed the main drive. Everything was backed up and it was time for a fresh install anyways. Upon setting everything up my iMac is super slow lags when opening finder etc. Now I am getting multiple warnings from Comcast/Xfinity that I have used all of my data for the month. I see from a system monitor that it is still downloading data. 400gb since my last restart. Is there any way besides logging out of iCloud to fix this?

Or does apple know about this and is ignoring it. I was thinking of resizing my internal HD to 200gb so that it would notice that there isn't any free space to download data.

I have the 2tb option with iCloud so there is a lot of items on there.

A few problems yes the iMac is from 2013, and yes I am running on Catalina but hear me out the system was running beautifully before the update. I was even able to run Motion and Final Cut with little lag.