Here's the difference between the EOS 5D Mark IV and the EOS R6 Mark II. It is down to battery drain. If you leave the 5D turned on, there's nothing else going on in the camera other than the top LCD.
On the R6, the IBIS module drains power when the camera is turned off. The magnets need that power to hold the unit in place. If you want your batteries ready to rock after a week away from the camera, take it out and don't shake the camera.

I personally don't like leaving batteries on chargers or a USB cable plugged in for charging for a long period of time.
Consider that a mirrorless camera sensor is always on when the camera is on. It isn't on a DSLR.
Canon chose to keep the LP-E6 form factor (For better or worse), but now it has the sensor draining the battery at all times. The EVF is also draining battery, which a DSLR obviously didn't have. The trade-off is, they killed the GPS to reduce drain to keep the battery form-factor and not really increasing capacity. Think about bluetooth, wi-fi and all that.