Input gain vs input meter in NDSP's official videos

hi there,
I heard I should leave my input level at zero or more recently, that I should add around 2-3 db of gain from the interface and reduce the level with the same amount in the plugin.
now, please take a look at the official video demonstrating the nameless x plugin, e.g at 4:33, 5:10, etc. more specifically, please take a look at the meter bar next to the input of the plugin. it goes so high that, in order to achieve that level I need to add at least 8db from my interface. moreover, nothing is subtracted from the plugin’s input, which in the video is still at zero.

what am I doing wrong?
as an inteface I use the QC, I also tried with a Clarett, but I get the same result. the bar does not rise above the half.