I saw a couple of posts from November 2021 to recently about this so thought I'd throw it in there. This started happening to me a couple months ago. I've been managing it by just playing with about 25% less battery than I am supposed to have (100+50 rather than 100+100). I always charge when fully shut down. I tried the USB menu method. I get 92+72 rather than 100+100. It always goes back to 100+55 or maybe 100+57, or once even 100+53. It's like the Elite Strap cannot fully charge the Quest 2.
I'm not willing to Factory Reset. I have too many settings that were honestly a hassle to get set up back in 2020 so I'm not going through that again. I saw reports of some people saying that initially worked while others tried it and it didn't help. I'm also not willing to UPS my headset back to them so they can send me back a refurb. I bought a new headset. I use it to a certain level. I have the right to have an exact headset and that cannot be guaranteed with a refurb. It's like rolling the dice.. it could be more used, or less used.
Posts seem clear that, after experimentation and deduction, Meta caused this to happen through one of their "battery optimization updates". I realize that it is unlikely that they will correct the problem with v41 or a future update.. but that remains my hope. If not addressed by them with a software update (the only action I will accept), I'll have no choice but to abandon VR. I can think of no worse scenario for them than to have anyone leave because of an action they did that is not being addressed that can be addressed.
It is unfortunate, but despite how badly performing my Android phone battery is compared to an iPhone battery, it still, after years and years, charges to 100%.