Could it be because there are less Jam producers in the UK because fruit is now left rotting in the fields?
"Haygrove raspberry and blueberry farm in Ledbury, Herefordshire is moving some of its growing to Yunnan province in China because of uncertainty over migrant labour. “It is one of many,” said Capper. “There are lots of businesses looking at other parts of Europe, South Africa, Australia, New Zealand, China. We are disinvesting in British production which is just appalling.”