jaisis are atually joshis and not differernt to others. but pn shah banned them from doing their job as jyotish since they once conspired with valley king and tried to kidnap his eldest son while hunting.
from then onwards ,jaisi bahuns were degraded from others and not allowed to perform rituals like public pujas and astrology works.
otherwise ,the upadhayas consider themselve pure since they didnt mix with khas race when they came northwards to hinduise the khas. the ones who took hinduism easily or married upadhyas became khas bahuns(both purbiya and jaisis).and the pure khas who accepted the thread became chetris while the ones who resisted became the matwali khas and dalits.