According to most etymological sources I can find, Rhianne Moll, the usage of “to suck” for “it’s bad,” is fairly new, the first documented written example dating back to 1908, in which it was a shortening of “to suck eggs.”
That usage would have been a class slur, given that very poor people were known to steal eggs from neighbors' henhouses, sucking them on the spot for nourishment.
However, the expression didn’t become prominent until the 1920s in the US, when it became explicitly tied to fellatio.
In fact, when I was a child in the 70s, kids were generally forbidden from using the phrase, because adults were all too aware of what it meant. It was generally a “dirtier” pejorative than it is now. The times were more surface innocent.
Interestingly, the alternative “hind tit,” which has different origins, is something I first encountered in the Marine Corps, which preserves some pretty special language.
“That sucks royal hind titty,” is still current in the Corps.
Different etymology, though.