Aduen

I assumed that GPIO pins are not even set nor part of the power off RTC circuit...?

I have recently run into this problem too. What I have found is among the 5 teensy 4.0's I have, the power consumption for the rtc varies wildly. This is measured with no external components for 5 different teensy 4.0's: 2x 92uA, 84uA, 46uA, 27uA...