Fatwa: Is Amazon FBA Halal or Haram?

I am an Amazon Seller. currently using FBA.
Amazon has its special day such as:
Prime Day, Black Friday, and Cyber Monday.

Prime Day is a discounted price for Prime member-only while Black Friday and Cyber Monday is for all customers.

Amazon tells the seller to provide a minimum 20% discount if a seller wants to participate on that special day.

my question: Is it Halal for me as a seller to participate in that event?