I’ve noticed my AirPod Max being stuck at ~74% battery and not wanting to charge any further. It’s running the latest firmware and I usually charge them on a (legit) usb-A-to-lightning cable connected to my monitor. Even keeping them connected charging overnight would somehow max out at 74%.
There are a few Reddit posts with other people facing the same issue with AirPod Pros (case not wanting to charge further than 74%) but no concrete answer or solution is posted.
For me, what helped, was to use a wall charger (doesn’t have to be Apple); it’s still using a similar usb-A-to-lightning cable. Letting it charge for a while managed to get it to 100%.
Why 74% and not… 75%? ¯\_(ツ)_/¯
Edit: as some people pointed out, this may actually be Apple’s Optimized Battery Charging. I am not seeing any notification though.