"Bohemian" got that meaning because French aristocratic youth saw Roma gypsy immegrants and just called them whatever the closest east European neighbors they thought of.
The fact that you think it is a lifestyle and not a people shows just how much history is lost. Somehow king Wenceslas got turned into a Christmas carol, but that's about it.
And I don't just "think" it is lifestyle. I checked multiple dictionaries and they all refer to it as lifestyle. And the way it was used, it was always used as lifestyle. I never even seen it being used for either czechs or gypsies.
It just ... exists. And contains capital.
And the word in English means what I wrote and not whatever you imagine it to mean.
To be clear, I am not saying that the word bohemian is used as a slur. I am merely finding it ironic that people who have qualms about things like "master" in git or "microagressions" have no problem using a word that was used in France to make light of any genetic eastern Europeans. "bohemian" as an artsy, free living, dirt poor hippy utterly erases centuries of history of a real people (not even the people they thought it applied to).
Moreover, bohemian literally means "a socially unconventional person, especially one who is involved in the arts". I am guessing you probably misread it as "gypsy" or "roma" where such stereotype might exist (tho negative stereotypes about them are much different nowdays afaik, but were be like that in past)