@Keith171
We've had a battery camera (the same camera used in the floodlight fixture) for over 3 years, plugged in with the optional power cable. Normally we cannot see the battery level, since Settings | Battery only shows "Plugged in" with an infinity symbol, but if we unplug the camera, the battery level has always been between 77% and 100%; there's no pattern to it, but the battery has always remained charged. (I just unplugged it now to check; it's at 100%.) The camera runs off of household current since it is plugged in; I don't know how or when Google Nest decides when to recharge the battery.
If your cameras are always connected to power, you shouldn't have to worry about the battery level. However, I have seen several posts in this forum from floodlight camera owners who have reported that the battery on their floodlight camera has depleted even though the camera is plugged in; that shouldn't happen.
