There are a lot of forgeries around at the moment due to the shortages caused by the pandemic.
what's a dodgy battery though?
Exactly what Charlie said. I have a Moli P26a that I posted about recently - 90 % sure it's a fake. It seems to have a max 1800mAh capacity, if that. I bought it brand new from a reputable retailer who wouldn't knowingly sell fakes.

It's on my top 3 too, decent well, flavour galore and more air than the Venna.
But I love a Minikin