I've never seen this happen before. The wells on the left side had corrosion in the well. The middle spark plug well has a lot of corrosion. The bottom left had mild corrosion and the top left (might have been top right) had light corrosion.
I'm going to clean it out a bit and use some dielectric grease on the seals but this was really some strange ISH.

Has this happened to anyone else before?

The spark plugs looked like the "TOO HOT" spark plug condition. Who knows if the previous owners ever changed them. My engine sometimes smells like it's overheating. It smells like heat but the car's temp gauge never goes over 45% and it stays around 40% when the car is moving. Hopefully putting some new semi quality plugs in and resetting the car cpu well fix this issue.

 

This happened to me recently when I had to change my spark plugs. I found corrosion on the well and I was told to put dielectric grease inside the spark plug boots. I did it to all 16 boots. In case of additional information I found out there are several applications of this dielectric grease not just for the plugs. Here: https://motoringcrunch.com/reviews/dielectric-grease/