Today B&H send email to customers who have purchased the Nikon EN-EL15b battery. Apparently, there was a bad batch and B&H is replacing the purchased batteries. Something is definitely going on because a few weeks ago I posted about the Nikon EN-EL15b battery being discontinued.
The Nikon EN-EL15b battery is used in the Z6, Z7, D7100, D7200, 7500, D500, D810, and D850 cameras.
Update #1: it seems that Adorama is also replacing some Nikon EN-EL15b batteries.
Update #2: here is the original Nikon article on how to spot a fake Nikon battery.
Here is the full text of the email: