When I replaced my stock chain on my Gen 1 bike, i went ZZZ and put a new sprocket on the F and R
I rode it around town a few miles and went to the track. Had maybe 15 miles on it and the thing was saggin like the photos above. Also found a broken tooth and a few chipped teeth on the front sprocket. I thought something was seriously wrong, and took it back the the dealer (less than 2k miles) They had it for a MONTH and changed the front sprocket and chain, replaced them with a DRZ chain that lasted 8k miles. It may have lasted longer, but I started with it back in the adjustment and ran out of adjustment. I Replaced it with another ZZZ and had no problems from there on out.
I think that the front sprocket was junk, broke a tooth and wiped out the chain. Just MHO