This is a known and unfortunately “expected” behavior. Until 240W chargers hit the market, the FW 16 can draw more power under load than the power supply can deliver.
I don’t mean expected as in a consumer expects it, I mean the max power draw is greater than 180W, and FW has admitted this on a post somewhere.
I’m running windows 11, playing Darktide at 1080p limited to 62fps, with mixed settings, my battery does not drain, even after several hours.
I’ve run FO4 and Skyrim too, but those aren’t demanding enough to cause drain.
Helldiver’s 2 when unlimited did cause drain, but at around 62fps limit again did not appear to drain.