That is a warning that the Tesla vehicle's 12V battery needs to be serviced, replaced. The 12V battery is covered by the 48 month new vehicle warranty so it should not cost you anything to have Tesla replace the 12V battery. When the low voltage message appears you have a few weeks (in theory) to get the 12V replaced before the Tesla vehicle won't start up or could even stop running while driving.
(Check with the Tesla Service Center near you but in the past this service costs ~$140 for Tesla Mobile Service (Ranger Service) to come to you and replace the 12V battery if not covered under the warranty.)
Until recently this 12V was a 40Ah deep cycle flooded lead-acid battery that powers things like the door locks, BT, LTE modem and the alarm when the Tesla vehicle is powered down (sleep mode) Tesla recently changed to using a 12V, 7.5Ah, lithium battery module (actually measures 15.5V) in late 2021 and now for all new 2022 Tesla vehicles. It remains to see how well the new 12V lithium battery module performs over time.