MS seems offers a few ways of back the decrypt key. One of them is uploading the bitlocker key to your account if you logged into ms account in that system. Or

MS seems offers a few ways of back the decrypt key. One of them is uploading the bitlocker key to your account if you logged into ms account in that system. Or you could write it down (Which isn't very useful IRL, I haven't see anybody actually write down recover code or whatever to paper yet.)