There's a fair number of misleading our outright wrong specs if your buying from amazon or the like. And even if you're buying brand name, the specs can be misleading. They often refer to the maximum output of all the ports, not the maximum output of a port.

So a 100 watt GAN charger might be able to deliver only 65 watts from it's main "laptop" port, but it has two other ports that can do 25 and 10 watts each. Still 100 watts in total, but your laptop will never get it's 100 watts.

Not every brand is as transparent about this, sometimes it's only visible in product marketing images instead of real specs. Real shady.