Because you pay the minimum every period

The interest that accrues is only the interest on the previous period's bill.

For example, if your limit is 5,000, then your minimum repayment amount for this period is 500. You repaid 500, so you owe the bank 4500.

If you haven’t paid off the previous period’s debt before the next period’s bill is issued, interest will start to be calculated on you

So you will have the lowest in the next period. The repayment amount is 450. The interest on the unpaid balance in the previous period is equal to your minimum repayment amount in this period!