for info, I called KLM today and requested a refund for two reservations (explicitly mentioning that I don’t need a voucher and prefer the refund).
Immediately after the call with KLM I received a confirmation “refund requested” for both reservations.

After a few hours I received a confirmation that the refund will be transferred to my credit card (for one reservation).
- Edited to add: next day this refund was processed on my Amex.

Still waiting for the second refund to process.