Corrosion Question

My electrician and I built the solar system on my house 7 years ago. Been working perfectly until late last year when 2 power optimizers but the dust. Fast forward to August of this year and the Solar edge inverter went bad. Called out a 3rd party solar repair co to determine why system wasn't working (was giving isolation errors + RCD errors). Knowledgeable tech pointed out issues with using wire nuts instead of Buchanan crimps. So I went around changing metallic boxes to plastic and redoing all of the connections. Noticed the corrosion on the ground lugs. It's only on this one where it's like this. Could this be an indication of something other than environmental degradation?