Try this, worked for me
Hi guys,
Came across this thread when looking into the same problem with my 2020 Macbook Air M1. Bottom of the laptop creaking/cracking noise. I found someone else mentioning that an Apple store removed the bottom panel and put it back on, and it solved it. Luckily, I didn't have to remove it, but just loosen all the P5 screws and tighten them again. If you still have this annoying problem, give it a try. $6 on Amazon brought my sanity back!
Good luck!
MacBook Air 13″, macOS 12.2