A reminder of Valve’s FAQ, given recent article on Websites trying to contradict (e.g. https://www.slashgear.com/1314340/steam-deck-plugged-in-overnight/):
If your device has been left on the charger for long periods of time, it may report less than 100% charge. This is normal. We allow the battery to slowly discharge after long periods of time under charge to optimize long-term battery health.
This is really good to know. Thanks for sharing!
I always avoid charging at night because of issues like this. On my Samsung I have it charge to 85 max, but I’d really like a way to tell devices that I’d need them by X time and they can target charging to max by that time to avoid battery damage.