For many conventional things that are considered standard "stereotypes" about groups such as physical appearance-related assumptions about sex or gender, age, race, nationality, or style of dress, accent etc., that the general public employs?
On the one hand, those in the rationality community emphasize the point to use whatever information possible, and that means sometimes using statistical info that would be called stereotyping (the famous example of statistical discrimination being car insurance for men and women, and other practical things such as avoiding tall men in dark alleys but not short women).
However, rationalists often also emphasize updating priors so it could be that even if initial stereotypes are held, a big deal is made of when to update more readily -- for example, when many people would keep on stereotyping a member of a nationality for e.g. not fitting the stereotype (e.g. are you really an X if you don't look like the X's I know, or have an accent I associate with X, or eat what I think of as X food?), it may be rational to update more readily (I just met a X person, I should update my preconceived notion of what X's are like instead of insisting they're not a real X for not following my stereotype).
Also, self-described rationalists are famously big on individualism (e.g. Scott Alexander's discussion of respecting individual preferences such as introverts vs. extraverts, ask vs. guess culture which is more about individual preferences than traditional demographic categories or cultures). It may be the case that some stereotypes are true on average (80% of X like some food vs. only 40%'s of Y's) but having an individualist, analytic mind (typically seen as more a WEIRD thing or STEM thing or "rationalist" thing, perhaps, though not always) vs. a collectivist, hollistic one might laser focus on the individual's agency and preferences (e.g. I don't care if Bob's a member of group X that stereotypically likes the food, Bob has already told me he doesn't like it, I'll take his word for it).