Yes Wh/L and Wh/kg are
Yes Wh/L and Wh/kg are entirely related via weight density.
Lithium ion batteries has a weight density of 2.6 kg/L.
Wh/kg = Wh/L / kg/L
For example 650 Wh/L equal to:
650 Wh/L / 2.6 Kg/L = 650 / 2.6 Wh/kg = 250 Wh/ kg.
I gather you do not know any math when accusing people.