Short term approaches
1. User to turn off iCloud manually
The user of the app can turn off iCloud for the App by doing the following on iOS:
Settings > iCloud > YourAppName
You will see a toggle switch to turn off iCloud usage for the app
Every user will have to do that by himself / herself manually
2. CloudKit Dashboard (turn off visibility)
Warning: Please test using a dummy container before you turn off your real container's visibility
Go to CloudKit Dashboard
Tap on the container name, a drop down would show up
Tap on Manage Containers
Warning: Please test using another container before turning off visibility on the real production container
Long term approaches
In the long term, you could try one of the following which ever suits you best
1. Separate Entity that doesn't sync automatically
On your CoreData Model, create a separate configuration and add an entity to that configuration.
Do all your saving into the new entity (which doesn't sync automatically), when you are ready move it to another entity which uses the default configuration which would sync.
You need to make changes to your store descriptions and new store description for that new configuration.
Refer: https://developer.apple.com/wwdc19/202
2. Don't save view context directly, instead use a child context (not 100% sure)
If you save the viewContext, it would save to file and would trigger a sync, instead create a child context to the view context and save it in the child context
That way your views will reflect the change but it is not saved to disk, but you need to save it before app quits or leaves a view so that user doesn't loose the data.
3. Change your logic and see how you group records and then save together
