Recommended Thunderbolt cable for MacBook migration

You don't need a Thunderbolt cable to do a migration from one Mac to another. No need to buy an expensive Thunderbolt cable that you will only use once.

The easiest, most successful way to migrate is to use an external drive. Create a backup of the old Mac on that external drive, and when you first setup your new Mac, use that drive to migrate your data. If you've already setup you new Mac, you can still use the backup drive with Migration Assistant to pull your file into your new Mac.

When your migration is done, you can erase the drive and repurpose it as the TM backup drive for your new Mac.

When looking to buy a backup drive, buy one that has twice to thrice the capacity of your new Mac.

Back up your Mac with Time Machine - Apple Support

Transfer to a new Mac with Migration Assistant - Apple Support

There is no such thing as a MacBook Air M5.

This has me wondering - what is the drive capacity of each of these MacBooks?

I ask because if the capacity of the destination is less than that of the original, then it's not surprising that Migration Assistant would fail.

Regardless, I'm happy to know that you did get this file transfer done. 👍🏽