Building savings contracts one-time interest rate changes, where is the catch?

For us, the BSP has proven worthwhile as residual debt protection, purely from the numbers. For us, the difference in interest rates between a 10-year and a 20-year loan was enormous. Since we owe 400k, after 10 years the risk was too high for me. With 2 children and many expenses outdoors (which were not accounted for in the loan amount) and so far having paid exactly 0 euros in special repayments, I am truly relieved by the current development. I am now at the present interest rate with the upcoming BSP interest. We still have 3 years left. It simply lets me sleep more peacefully (to me, the closing fee is worth it) and as I said, purely calculated against each other in terms of numbers, it has paid off for us.