In that previously posted link, it says that Yiddish was looked down upon, as being lowbrow and unsophisticated:
In the aftermath of the Holocaust, the cultural affinity of most American and other Western Jews was for the emerging State of Israel and Israeli Hebrew. Moreover, Yiddish often had an image of “greenhorn†lack of sophistication and lowbrow humor; its use was associated with failure to climb on board the American socioeconomic ladder of success. Starting in the 1960s, attitudes toward Yiddish began to change, influenced by several factors including the gradual death of the last masters (and of Yiddish-speaking parents and relatives) that evoked nostalgia for the “old countryâ€; growing consciousness (and knowledge) of the Holocaust; a recognition that Israeli Hebrew was now secure and that its proponents need not “fear†Yiddish; the changing evaluation in the United States of black and other ethnic cultures; and an emerging scholarly consensus that saw a great world literature in Yiddish prose, poetry, and drama in 150 years that can schematically be dated from 1850 to 2000. The Nobel Prize awarded to Isaac Bashevis Singer in 1978 was a prime watershed in reversing the tendency to stigmatize the language in the major Jewish communities that themselves hailed almost entirely from Yiddish-speaking East European Jewry.
I just speak not as an expert but as a sabra Israeli whose families come from France and Poland/Germany.
I vaguely remember you could get fined in Israel for public ally speaking in Yiddish, but maybe it was just a social thing. There was a huge push to speak Hebrew and be a unified people.
I do know my grandmother would yell at my grandfather for speaking Yiddish at home.
Some Haredim refused to speak Hebrew casually, and stuck with either Yiddish or English on the grounds it is a holy language and not fit for “selling cars and cabbages.” They’ve pretty much lost their war except in NYC.