The Unwanted Playlist Transfer
Historically, macOS relied on iTunes to manage iOS devices. Now, that functionality is built directly into the Finder. When you plug your iPhone or iPad into your Mac via a USB cable (perhaps just to charge it), macOS often assumes you want to perform a full synchronization. If your settings are configured for automatic syncing, your Mac will immediately begin transferring your entire Apple Music library, podcasts, and local audio files to your mobile device. If your iPhone is low on storage, or if you simply use streaming services and don’t want gigabytes of local MP3s cluttering your phone, this automatic background sync is highly frustrating and can take several minutes to cancel.
Disabling Automatic Finder Synchronization
To stop macOS from automatically syncing music and media to your iPhone when you plug it in, you must adjust the device management settings within the Finder.
Connect your iPhone or iPad to your Mac using a USB-C or Lightning cable. Open a new Finder window. In the left-hand sidebar, under the “Locations” section, click on your device’s name. If prompted, “Trust” the device on both your Mac and your phone screen. You will now see the device management screen in the main Finder window. Click on the General tab at the top of this view. Scroll down to the section labeled Options. Look for the checkbox labeled Automatically sync when this [device] is connected. If this box is checked, click it to remove the checkmark. Click the Apply button in the bottom-right corner to save the changes. From now on, your Mac will only charge the device when plugged in; it will never initiate a media sync unless you manually click the “Sync” button.