text message forwarding

To stop syncing, you would need to log out of your Apple ID on that device. Backing up to iCloud is not directly related to syncing to iCloud.

Also to make sure I understand. Which types of "text" messages are you referring to: iMessages or SMS text messages. The latter would only "forward" to a Mac if enabled to do so on an iPhone.

This is exactly how iCloud works when you are logged in with the same Apple ID on each of these devices. They are not technically being forwarded, but synced, between your devices.