Battery Health Management Issue

Hi,

After updating to 10.15.5, my Macbook Pro (2019) is doing some odd things with the battery.

Without ever unplugging the mac form the charger, the battery goes form

100% to 90% (very slowly) and then back to 100%.  It stays at a 100% for some

hours and then the whole thing repeats.

Is this the intended behavior? 

Just to be clear:

* Battery Health Management is ON.

* While the battery discharges, clicking on the battery icon I get: Power Source: Power Adapter

* I have thoroughly checked the charger and the cable and there are no problems there.

* The OS is up to date, in fact the problem started after the recent update.

* I haven't changed any of the default settings regarding power management.

Thanks