"Ts4 Downloading from One Drive" in the middle of my gameplay

@valley_joe1  The simplest fix is to disable OneDrive completely.  If you do use it for other purposes, you can merely disable its automatic syncing to cloud storage.  Either way, your Sims 4 files should all be stored locally on your hard drive, not in the cloud.

https://support.office.com/en-us/article/turn-off-disable-or-uninstall-onedrive-f32a17ce-3336-40fe-9c38-6efb09f944b0

Before you do anything else though, move your Sims 4 game folder out of Documents\Electronic Arts and onto your desktop.  You can move it back when you're done fiddling with the OneDrive settings, but this way, you won't accidentally delete the folder or leave it only in cloud storage and not on your PC.

So if I disable syncing, will I no longer be able to sync anything to my onedrive? Because I do use it for work and school purposes. Say if I moved everything to my desktop, and OneDrive was still on, and I open up the sims 4, will everything pop back into my onedrive again? Or will it remain out of my OneDrive?

@valley_joe1  If you disable automatic syncing but leave OneDrive enabled overall, you'll be able to manually sync whatever files you want.  It just won't happen on its own.  If you move your Sims 4 folder onto your desktop, the folder shouldn't be synced anymore, although OneDrive may still retain a copy (I'm not sure what happens here).  But the game won't read the data in that folder anymore and will create a new one in Documents\Electronic Arts, which will also be auto synced unless you disable the feature.

Given the error you're seeing, it's pretty obvious that OneDrive's sync feature is causing problems, so the question is how to intervene in the way that's most convenient for you.  Maybe you just disable auto sync while you play and reenable it later; maybe you leave it disabled and manually upload what you need.  But you do have to change some setting, or you'll keep getting errors.