Geek Bar Pulse X Juice Level

So I took apart the Pulse X from Geekbar which had a 5% level and inserted a near brand new foam pad with juice which had about 80% juice as it showed from the one I took it out of. After inserting it into the second one, the level was stating it has only 5% even though it should have been technically 80%.

Am I bugging, or is Geek Bar juice level counter just absurd and more of their circuit counting the puffs and not really the juice it has in its cartridge?