System Bootloader and Retaining the Last GPIO State

[SKape]

I have a problem I can't solve.

In a previous project, I used an STM32L4A6 and set the PC8 and PC9 lines high before entering the system bootloader. After starting the system bootloader, these lines remained high. They were used to maintain power to the device.

In the new project, the MCU was changed to an STM32F446. I used the PD10 and PD12 lines to maintain power after confirming with the AN2606 that they were not being used by the system bootloader. Unfortunately, after starting the bootloader, both lines are reset.

Why does this happen?

[mfgkw]

Do you use the default bootloader?

AN2606 says in "Table 84.STM32F446xx configuration in system memory boot mode", it uses USART3.

[SKape]

I'm using the system bootloader built into the MCU.
The An2606 says that the 446 system bootloader uses USART3 on PB10/PB11 and USART3 on PC10/PC11.

I'm using the theoretically free PD10 and PD12 lines.