I’ve had the charge limit on 80% since it became available as I leave my deck docked for long periods of time, but it doesn’t seem to be working since every time I get it away from the dock it shows 100% charge. Also the charge indicator gets stuck now until I reboot the deck, but that’s a separate issue…
I don’t have a steam deck, yet, but my pixel also has this battery feature.
There’s some info in the settings, about the need to let the battery go to full 100% every now and then.
It shouldn’t happen that often though.
Once i had it go to 100% three times in a row, but other than that it’s always 80% and sometimes, often the first load after a reboot, it goes to 100%.