Here in Canada, underwear, top and bottom is called "next of skin" and you are not required to return any issued item in that category. I noted this was a rare event with them, mediated by Covid shortages in their supply line and used underwear is cleaned and assessed for suitability for re-issue. There is a maker in the USA, 'under armor', not related to army use, but it is a good rabbit hole for stuff I did not know...lol https://en.wikipedia.org/wiki/Interceptor_Body_Armor

and the Russian counterpart...

https://en.wikipedia.org/wiki/Ratnik_(program)