Downgrade from Monterey to Big Sur? M1 Issues with Monterey

Does anyone know how to downgrade from Monterey to Big Sur?

I was experiencing some kernel crashing issues and I was told to upgrade to Monterey by apple support. Upon upgrading to Monterey my computer went into recovery mode and I lost all of my files. From here my MacBook Air could not find a network and started having network issues unless I tethered my Air into a network via ethernet.

I took my machine into apple and behold I was less than a month out of warranty. After talking to 2 support people and 2 managers they wanted to charge me $425 to repair what they think is a faulty logic board. They offered for me to trade in my device for 60% of what I paid or to pay out of pocket for the repair. The computer is 13 months old and worked mostly fine until a software upgrade!

Has anyone else had a problem like this? I currently have no network settings yet I am on the internet and I can use the internet. Seems like a software issue and apple is not helping.