Migration Assistant "made my new macbook air old"

Starting over means you would need to erase the Mac first.

Erase your Mac and reset it to factory settings - Apple Support

You can simply start over from the beginning and leave that option de-selected.

MA seeks to present you with a new Mac along with a new macOS but leaving an overall appearance that you had been comfortable using. The alternative risks presenting users with a less than comfortable experience. In the end it's up to you.

One Size does Not fit All 

If the new computer is going to be the Apple Silicon M1 / M2 / M3 /M4 Equipped Computer - would suggest Only Migrating the User Account and nothing more.

Some have had success and usually are well seasoned veterans who are well versed in trouble shooting  like @John Galt and other

Others have been left with a mess when Migrating everything.

 Issues that may have existed on the older computer will be migrated to the New Computer.

This would badly pollute the new Original and Pristine installation of the new OS which you appear to have experienced..

Applications, extensions and Software Drivers may or may not even work on the new computer.

IMHO - it would be best to only install new application etc Directly from the Developer or the Apple Apps Store.

Due Diligence on New Applications and make sure they are Sequoia / Sonoma / Ventura / Monterey / Big Sur compatible and factor in the ARMs CPU of the Apple Silicon Computer