It also doesn't help that ACPI is a badly-designed mess of a standard. I remember that in the 2010s one of Apple's selling points was that their laptops had sleep and hibernation that worked every time. Heck, MacOS X could even decide intelligently when to do which. This mostly worked because they fully controlled the hardware, firmware, and software. Other laptop manufacturers could just take their best stab at implementing ACPI power states and hope their implementation matched Microsoft's.

Microsoft tried to solve the mess by introducing the S0ix ACPI state (aka "Modern Standby"), which was defined in a way that could actually be implemented without too much guesswork. Unfortunately, this was during the Windows 8 era when Microsoft decided that laptops should be more like smartphones so S0ix is much closer to turning your screen off on a phone than to actual standby.

The system randomly waking up and deciding to do work is an explicitly intended feature because what if you get a Teams message while your laptop is in your bag? Sure, you might say that you'd either have Teams on your phone or wouldn't immediately care but that kind of thinking won't get you anywhere within Microsoft. Also, Windows actually has very little restraint about what it does when it wakes up so it might decide to install a heavy update or an application might decide it's important enough to do work right now. While the laptop is in your bag. Cue you wondering if the laptop turned off because the battery's empty or because it overheated.

And to make things worse Microsoft specified that in order to be allowed to use Modern Standby, the device must not offer S3 (sleep/suspend-to-ram). Some manufacturers still allow you to enable S3 but it's a legacy feature that's even less well supported than before.