Don't want to release my inheritance money

My sister passed away on November 25, 2025. She had a Discovery Life Benefit Cover, and I was one of the beneficiaries. The funds were deposited into my account this week, but FNB put a hold on them. They are requesting paperwork to verify the source of the funds and said they will decide if I can access the money. It's infuriating to think that FNB will determine my worthiness to receive the benefits from my sister's life insurance. I have no family left; it was just my sister and me for many years. Now, FNB is deciding if I can receive the money that my sister left for me. I'm so upset and crying—I can't believe this is happening! It's shocking!