Top-up vs. 2nd loan agreement

Hello, I am a DKB customer and can immediately apply for a loan within online banking, which ideally will be approved and paid out immediately. I’ve had a loan for a long time that I wanted to top up today. I’ve done that before, and the increase worked. But today it was rejected by the bank. Although I entered the transfer account at the DKB directly again.

Now for the odd point. I requested the new additional amount as a new loan and it was approved and paid out immediately.

Why is that so? Is it nice????