Bug spray = petroleum distillates = bad stuff. I'll give a +1 on 303, but only AFTER having thoroughly cleaned the pad first. Without going over the instructions again I consider it more as a protectant than cleaner. Although not identical to the OP's case, I brought back a badly mottled sun-damaged pad using several different cleaners - each one
lightly to take advantage of their individual properties: dish soap, magic eraser, 409, vinyl cleaner...etc. I think the right approach is being used, but more different products used lightly can address the petroleum "bleaching" some more. Or not. Then, it's going the SEM dye repair route as offered earlier above. Mine is 25 years old, so a much newer pad will have dried out less and allow easier leveling of finish. The spotting looks pretty tough, but I've seen worse brought back. After a few hours poured on it, the results will make it "less than the worst" thing anyone notices about the car. As last resort the leather/vinyl cream conditioner and/or current formula Armor-All. Some pics worth a 1k words each - good luck:
Dirty as hell:
Much Better:
With 303 - note matte reflective increase:
Parting thought: a dead spider laid near the defroster will guarantee the stain immediately becomes less noticeable.