I have noticed a similar change in my model 3, maybe for the past week or so. Whereas I used to be able to unlock any door or the trunk by approaching with the phone in my pocket, now this only works for the driver side front door. If I take the phone out of my pocket and turn on its screen, I can unlock any door or even the trunk on approach.
Over the same time period, I have also noticed that sometimes I enter the car with my phone in my pocket and am unable to shift from “park” into “drive”. At first I thought there was some bug in the software. But some of these times the car display would also ask me to touch my keycard to the center rest. I found that if I unlocked my phone, the car would respond to the shifter.
As with the unlocking of doors and trunk on approach, the shifting into “drive” used to proceed with my phone in my pocket, undisturbed. I am not sure what caused the change in recognition / response.