Very shortly after we drove away from the 2019 BigJimny meet, I heard a very loud bang from somewhere underneath BigJimny. I pulled over and could not see anything, the Jimny still had drive but was giving out a knocking noise.
I suspected the CV joints as they have been clicking for a long time, however I found that the noise was coming from the rear diff (see video below, you can hear the knocking noise if you ignore the disc scraping noise)