From 2022 Passport Owner's Manual, page 209, regarding rear seat heaters:
The power mode must be in ON to use the seat heaters.
There is no heater in the rear center seating position.
Press the seat heater button:
Once - The HI setting (three indicators on)
Twice - The MID setting (two indicators on)
Three times - The LO setting (one indicator on)
Four times - The OFF setting (no indicators on)
When the power mode is turned on after it is turned off, the previous setting is maintained.
Which is the same information (except the sentence in bold) that is printed on page 207, which references the front seat heaters
So 2022 Owner's Manual makes zero reference to rear seat heaters only working when front seat heaters are operating.
Perhaps this is an opportunity to 'train' the techs and service advisors