Since I don't see the whole schematic, I cannot make any definite conclusions. I can only suppose that the whole circuit (both red and green rectangles) is meant to add some small bias voltage, taken from the PWM_OUT0 signal and then rectified on the R6/C225 circuit, to the feedback point to control the DVDD_CORE voltage with an external PWM (the source of the PWM_OUT0 signal).
Please note that this is only my own supposition and I cannot claim that it is true in any way.
Have a great day,
Artur
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