Did a major overhaul washing of my E since it's been too cold over the past month or so, this past Sunday....

I used Meguiar’s NATURAL SHINE VINYL & RUBBER PROTECTOR on the black exterior panels - not too much and made sure it was all covered.

Yesterday I noticed a little bit of dots all over the black panels and today it looked a little bit worse - I didn't put a ton on either -

any ideas? Anyone else not have great luck with this stuff? I read a lot of people did have good luck with it so suprised of my results...

Might be due to the product you used? I have never used that product, I have always stuck with "back to black" or 303 aerospace.

I'm not familiar with that particular product either...
But it sounds like a typical 'Protectorant' - it's designed to just sit on the surface, and protect the plastic. Read the label, and see if it's silicone based, like Armoural...
Silicone is not a good product to put on plastic - it will eventually discolour and causes pitting in plastic - it eats it....