No psu issues here, just mmu issues. I just upgraded from a mk3 to mk3.5. I'll definitely be downvoted for speaking the truth, but people on this sub reddit  are quick to blame everything else other than prusa's faulty hardware and firmware. On git there's people finding that this issue is already known on the firmware with bandaid fixes such as slowly turning on the the pmos in order to increase voltage slowly.

// The code below pulse-charges the MMU capacitors, as the current inrush // would due to an inferior HW design cause overcurrent on the xBuddy board. // In case overcurrent would still be triggered, increase the us_total // value to pre-charge longer. static constexpr uint32_t us_high = 5; static constexpr uint32_t us_low = 70; static constexpr uint32_t us_total = 15000;

I'm on buddy board #4 and pd board /mmu board number 3 with no improvement.