Distearoylethyl Hydroxyethylmonium Methosulfate is a quaternary ammonium salt.
I think that’s just saying it’s a salt, which would have a softening affect in conditioners or shampoos. (Water-softening, since a lot of people’s water is hard). I don’t think it is irritating or harsh.
EWG cosmetic database gives it a concern rating of 0, meaning there is no concern.