I found multiple bolts on my Tab 400 that have these huge washers that don't look right. Most of the washers on the trailer are properly sized, but a few of them look like this. The bolt is also twerked to an angle here a bit and I'm worried that whatever this is bolting together has shifted, these aren't even the most angled bolts.
I told Nucamp about this and they say it is normal, they are "over tightened lock washers". I have never seen lock washers that look like this, though.