mathaetaes: It sounds like they rolled <10, reloaded from a save, tried again and rolled <10, repeat.
I don't think Karmic dice affect that, since they're reloading the game.
Some games seed randomness and store that seed in the save so you can't save scum the skill check rolls. Not sure if BG3 does that or not I've never save scummed BG3 yet to find out. I just let the rolls play out.
You can absolutely roll low values over and over, believe me it happens in pen and paper as well. I rolled 3 1's in a row last week and then one of my party members rolled two 1s right after me.. bad luck.
Outside of the feature where you can have it help you they don't cheat.. it's random.. rolls are rolls and you can def get a string of bad ones