If you login as a blank account, for example if you want to mod something and test it out with something like eclipse, it will have a 0 for the access code, but when you go back to the launcher it asks you to log back in, this has never happened in older versions though.  (I have keep me logged in too)

Please Note this does not happen 100% of the time, its more of a 50/50 Chance + how long you haven't been on minecraft or you use a launcher like lunar or badlion.