Hi foggyhead,
From what you described in your original post, we recommend you try the steps in the link below since you need help transferring data from your iPhone 8 to your iPhone 14.
Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad
Next, we'd like to show you how to perform the recommended troubleshooting steps via the link above. Please click to open the link, then read through the steps in the section titled "Select a method."
Next, select one of these transfer methods.
Quick Start: Use your iPhone or iPad to automatically set up a new device.
iCloud: Transfer your data and purchased content to your new device from your previous device's iCloud backup.
iTunes or Finder: Transfer your data and purchased content to your new device from a backup you made with iTunes or Finder.
We recommend the steps above because they will show you how to set up your new iOS or iPadOS device from a backup of your previous iPhone.
If you're still experiencing the same issue, contact the community for more help.
Thanks for using the Apple Support Communities.
Cheers!