Over a decade ago it was common for tablets of any kind to not be able to hold a charge while plugged in when pushed to their limits.

Perhaps with some tablets, but the iPad 2 and first gen shipped with an adapter (20W?) that didn’t allow that to happen, in my experience.

It was a 10W. I ran many system-intensive games and only remember battery drain when using a smaller power brick, but never ran Geekbench on loop to test that.

These iPads I'm using are ipad2, well over a decade at this point

HA on my MacBook occasionally pushes M1 to its limits. I suspect it's the dashboards with too many items.