@OVER
Mine purchased from JB Hifi too, Pixel 4XL. I thankfully haven't had any problems with mine yet, aside from the fact that "Ok Google" stops working. This is apparently a known issue if you change your language from US English to AUS English. You can "wake it up" for a couple of hours by squeezing it, but after a while it stops working again.
But no battery issues, no. I don't charge by the cable, I charge each night on my Pixel Stand.