Hi merp,
welcome to the Apple (user-to-user) Community.
Re: "Airpods Max constantly crashing/ not waking from sleep"
Wondering if the computer / device(s) you use with the AirPods Max are up-to-date with the latest MacOS / iOS / iPadOS software, so that the firmware on your AirPods updates automatically to retain compatibility.
Apple support's article: Connect and use your AirPods Max - Apple Support
says:
"You need at least one of these:Â
iPhone or iPod touch with iOS 14.3 or later
iPad with iPadOS 14.3 or later
Apple Watch with watchOS 7.2 or later
Apple TVÂ with tvOS 14.3 or later
Mac with macOS 11.1 or later"
Here's how lower power mode is supposed to operate:
How to charge your AirPods Max and learn about battery life
says:
âś˝. If you set your AirPods Max down and leave them stationary for 5 minutes, they go into a low-power mode to preserve battery charge. After 72 stationary hours out of the Smart Case, your AirPods Max go into a lower power mode that turns off bluetooth and Find My to preserve battery charge further.Â
✽. If you put your AirPods Max in the Smart Case when you're not using them, they go into a low-power mode immediately to preserve battery charge. After 18 hours in the Smart Case, your AirPods Max go into an ultra-low-power mode that turns off bluetooth and Find My and maximises battery life.
You might want to make sure nothing (a speck of dirt or wax) is blocking access:
How to clean your AirPods, AirPods Pro, AirPods Max, and EarPods - Apple Support
If needed: How to reset your AirPods Max - Apple Support
If you wish:
Webform for feedback to Apple: Feedback - AirPods - Apple
________________________________________________________
How to: Find the serial number of your AirPods – Apple Support
Enter serial number to:
Check Your Service and Support Coverage - Apple Support
More info:
About Warranty: Legal - Hardware Warranties - Apple
About Replacement : AirPods Repair & Service - Apple Support
 If you decide to visit an Apple Store:
 a Genius Bar reservation is recommended:
 Genius Bar Reservation and Apple Support Options - Apple
_____________________________________________________
Resource:
AirPods User Guide – Apple Support
More support . info. if needed:
AirPods Support Website:
Find all the topics, resources, and contact options you need for your AirPods....
AirPods Support - Official Apple Support
All the best :-)