sorry wrong forum.
Why ask? Just connect all Hands and try again.
Edit: :-) Automatic word correction: Of course I meant: GNDs.
SMH said:STM32H745
This is a question for ST - nothing to do with ARM.
ST should have documentation on PCB design recommendatioons for their chips ...
https://www.st.com/en/microcontrollers-microprocessors/stm32h745-755.html
https://www.st.com/content/st_com/en/support/support-home.html
community.arm.com/.../158950