Your headline is a lie.

You suspect they used a different screen brightness, but you don’t actually know.

It’s easily possible that the different laptops have a different number of clicks in their bightness settings since they use different panels.

I agree that it would be better for them to use a nits value or some other objective measure.

You however don’t know what the value is and so have made a false claim with your headline.

How about updating the headline to a question or a suspicion?