I've just noticed on my tab s7+ 5g that the protect battery option is broken putting it on it still will charge upto 100% like it would if wasn't turned on, as it should only charge to 85% then pause but it doesn't. I've tried few times putting it on and off and restarting my device but still charges to 100% on turned on.
I do know the device care had update to it most recently think that has broken this option in it.
Although it shows 100% it still is only charged to 85%. It actually tells you it will show 100% when it's charged to 85%, where you toggle the feature on. Had mine over a year using protect battery feature, its always shown 100%.