DL cut back far too much and their algorithms are being particularly revenue-happy.
That, plus don’t forget that DL is still seat blocking while AA is not. Multiple people have reported higher than 2019 prices in DL F very recently despite the service cutbacks.
With regards to the Y-only availability, this could be because schedule changes are coming in about 24 hours (on Saturday). This usually happens to a flight if it is changing or being cancelled, or it is brand new and has just been added (it takes them a few days to add the lower fare buckets in, for whatever reason).