iPhone backup on finder stops

It sounds like you're having trouble with backing up your iPhone using Finder on your MacBook. Sometimes, interruptions in the backup process can happen due to various reasons. Here are a few steps you can try to troubleshoot the issue:

1. Ensure that the cable you're using to connect your iPhone to your MacBook is in good condition and properly plugged into both devices. Also, try using a different USB port on your MacBook to rule out any issues with the port.
2. Sometimes, a simple restart can solve many connectivity issues. Restart both your iPhone and MacBook and try initiating the backup again.
3. Make sure your MacBook is running on the latest versions of macOS Big Sur. Updates often contain bug fixes that might resolve backup issues.
4. When you connect your iPhone to your MacBook, you might see a prompt on your iPhone asking whether to trust this computer. Ensure that you tap "Trust" to establish a secure connection.
5. On your iPhone, go to Settings > General > Reset > Reset Location & Privacy. This won’t delete your data but will reset your location and privacy settings, which might help with the backup process.
6. If possible, try connecting your iPhone to a different computer to see if the issue persists. This can help determine if the problem is with your MacBook or the iPhone.
7. Ensure that there's enough storage space available on both your MacBook and iPhone to accommodate the backup.

If none of these steps work, you might consider contacting Apple Support for further assistance. They can provide specific guidance based on your situation and might have additional troubleshooting steps tailored to your setup.