I would be systematic and swap part out one at a time.
If both brakes do it, then just get one brake sorted, then move on to the next.
Rotors and disc are the first suspects so I’d be inclined to try different pads on one brake and go from there to swapping out a rotor too.
After that your back to checking alignments etc again, but it sounds like youve done that to death already.
I fitted the DB5’s myself and found I had to use a couple of washers to get the pads lined up on the rotors to my liking. That said, even before the washers were fitted, they were still quite.
Good luck either-way! (Oh, im currently running sintered Uberbike pads on my DB5’s and they are lovely and quite on the Centerline SRAM rotors…. though I think your caliper is different admittedly.)