It says 'Net' salary. So after constituency running costs, travel, board, lodgings, food, entertainment etc etc etc are taken out.
Probably a hundred quid a month will be 'donated' - then that will be used as a tax write off somewhere else!
Her mum is already here - her husband got citizenship after the war.
Her son was included in her visa application so has ILR as well.
The rest of her family are hill Billy's drinking moonshine in rural Poland - although none would qualify as "immediate" family to be granted a visa now anyway, but could have moved if they wanted to with no restrictions between 2005 and 2019.
My other half is Polish. Given the opportunity she would most definitely have voted for Brexit. Maybe she's just bitter that she had to pay circa £1k for her visa in the 90's whilst everyone else gets in for free?