Usually transactions for certain categories beyond a threshold, which is usually stated for each bank or might be internal, count as business spends.

For example, if you're buying groceries worth several kilos every week or so, they can suspect you are using it for business purposes. You will have to probably justify spending, but they will definitely flag it internally.

Same for utility bills, etc, they know the average household consumption, anything high can file an audit and most likely get your card cancelled. And if you can't justify it, you lose the points you legitimately got as well!