Loans from the CB are just one part of a bank's liabilities.
Their main liability is deposits.
Deposits can cost up to 3%.
Sure, but the "banks are losing money on trackers" meme comes from the time in 2008 when EURIBOR was over 4%.
You could equally say "banks are losing money on deposits".
As a tracker customer with a performing loan it's hardly my fault that the bank is having to offer 3% to attract the rats back to its sinking ship.