I don't have that vehicle, but - are they capable of Over-The-Air software updates? Maybe you received an update that has this bug in it?
OR - when you enter the password, is there a "Remember Me" checkbox you have to tap?
OR - maybe power is being intermittently lost to the radio unit, causing it to lose the password?
Just guessing here ...
2011 Equinox 1LT (dlvd. Jan 2011): Summit White / 3.0 L V6 / FWD / Pioneer Stereo / 18" Wheels / 143k miles [15-MAR-2020]
2002 Impala 1LT (dlvd. Jun 2002): Summit White / 3.4 L V6 / FWD / Cassette-CD Combo /230k miles [15-MAR-2020]