The 3dB bandwidth (= 50 % power) starts at between 600 and 700Hz and finishes at between 1700 and 1800 Hz.
So the BFO offset is in the normal range imo, it is just a case of a narrow xtal filter.
This has been reported before. If you are not afraid of surface mount soldering it is an easy adjustment.
Not a major issue in my opinion.
Just makes the rx an Tx signals sound narrow. Better for DX.