Whether intentional or not. They were exposed to something very corrosive. You're going to find that something caused the corrosion to happen.
For all I know the way the armor was added, the glues used, what it was made out of, what it was washed in after assembly, and the box it was kept in.
Like I said I've seen some weird shit happen with wire, and terminal ends whether male or female. The use of the WRONG solder mainly acid core vs
resin core will do exactly what you see over a period of time or use acid as wash/pre-treatment before soldering the assembly.
I've seen people who are assembling machines and there are a few different types of solder used. I've seen them mix up the solder and grow
barnacles as a results. Solder up a HP plumbing joint and then grab the wrong spool of solder and solder in a sensor. I've seen that quite a few times.
The bad part is it's usually UNDER some shrink tubing in a 2" thick analog loom with 200 wires in the loom.
Digital machines certainly have their advantages, BUT at one end or where sensors are required, those wires are analog plugging into a junction box/cann bus
node for digital wiring and a voltage + & - wire.
BTW I'm NOT saying you did it, I'm saying someone else did. I'm a retired mechanic, and all I ever did was fix someone else's mistakes. I did get pretty pissed
when they would take a hammer to something and cost 10K when they just needed to turn something in the opposite direction.
Regards