earlier someone cited the chofetz chaim saying it is lo yilbash. is that a halachic prohibition?
That’s what it says in Chofetz Chaim perek 6.
He also writes about how important it is for a Jew have a beard in Nidchei Yisroel & Zachor Limiriam. In Sefer Hamitzvos Hakozer he’s machmir like the Chinuch and says a Jew who takes off his beard is also oiver Lo Sillbash and Chukas Ha’akum. In Machane Yisroel he says a Jew in a goyishe army that has no choice but to take off his beard, should let a goy shave him. He wrote an entire Sefer, Tiferes Ha’odom, on how important it is for a Jew to have a beard. He writes there that a Jew that takes off his beard is mavatel a tzivuy Hashem. He writes that no chillel Hashem is comparable to one who brazenly goes in public with a clean shaven face. He does not says oiver an issur d’oireisa, but rather such a person walks down the street and proclaims “The tzivu Hashem of Lo Sashchisu is not important to me.” In perek 2 he writes that shaving is worse than eating treif.
If there is any error in these citations, please so state.