Thanks for your comment.
I removed those two components and checked PB_IN. Surprinsingly it shows 3.39 V (even though VDD_3V3A is low, checked). So this is leading me to think that maybe the manufacturer didn't do a good job.
USB_DC is for now the only line containing voltage so the only way those 3.39 V reached PB_IN is through short-circuits i guess.
I'll keep looking into it. Let me know if something comes to your mind.