Why did the icons change from colourful to black?

[neurotypical]

I've noticed the icons went only black basically, they look slim and simple, but I miss the kinda goofy design with the cute colourful icons lol. I also liked the green "V" check marks as confirmed... i just wonder who and how did this design took part to replace the old design.
Will we have different skins for the program in the future?




PS: In linux it seems they are blue but in windows they look black for some reason. With that blue color it looks pretty cool.