An hourly paid job that has a 'bonus rate' attached to the hourly rate. Paid monthly, each month you'll be paid the bonus rate as long as you aren't off sick. If you're sick or absent, you'll lose the bonus rate.
Aibu to think this is not legal? It's punishing people for being sick.
Ofc there are always people who take the piss and skive sometimes but we're human, sometimes we are unwell and it cannot be helped.
I find it outrageous and have never heard this before.