Uncle Ben is right. It has turned out to be minhag among Bnei Brak people, and has spread to Bnei Brak type of people elsewhere in Eretz Yisroel. A few people who learned in Ponevezh even do it here in England. They wear a frack (as we Brits would spell the way it’s pronounced) at their Chasuna and then on Yom tov and chol hamoed. Many “Bnei Tayreh” have taken this on, and it gives yom tov a special feeling, with then with their fracks and Belzer chassidim wearing white socks. There is alays a discussion when Shabbos follows Yom tov, do you change back into regular shabbos clothing, or keep the nicer clothing over shabbos as well.
There is a well known anecdote which may be true. Rav Eli Gurwicz, son of the Gateshead Rosh Yeshiva is married to the daughter of Ponovezh Rosh Yeshiva Rav Berel Povarsky. When he was going to come to Gateshead for Yom Tov for the first time his mother told him, Come for Yom Tov but leave the frack in Bnei Brak.