@thor oh yeah, extremely sad https://www.youtube.com/watch?v=kWRhdN2XusA

Jokes aside I kinda know what you mean, the more whiny, emotional way of singing, but we don't read it as sad (unless it's actually sad of course), we read it as just melodic and maybe more emotional than your standard western pop. A lot of slavic songs are what we call "skoczne" in Polish, translated literally as "jumpy" and more semantically as "lively" – fast-paced rhytmic songs for having fun where melodic/whiny vocals spice up the experience instead of making it sad.

The first example is from 2001 as the further into the current milenium you go the more western influences you see and less traditional ways of singing, but there's still bands that preserve and modernise them like Percival, the folks who made the Witcher 3 soundtrack, or Żywiołak who made this https://www.youtube.com/watch?v=BcGCmFJVng0