For those who don't know what the fuck "Liquid Glass effect" is: it's a sort of frosted glass look that apple uses for their UI.

It's being sold as the best thing since sliced bread. Googling it felt like I entered a parallel universe.

Windows 7 did it like 15 years ago

Windows 7's had more character.

Windows 7 built a design language around it, transparency was never the main attraction.

Which is smart. Contrast is king, especially on consumer hardware where grandma might not see too well in her late age. It wasn't the glass effects of Vista or Yosemite that appealed to people, it was the high-contrast UI elements and skeuomorphic design elements (neither of which are present in liquid glass).