Why OpenSea is asking me to sign a transaction and pay a fee for setting royalties?

Manifold Support Questions
1

I set up my royalties on my Manifold contract and I have added the Operator for OpenSea:

image
image1677×1330 166 KB

But when I go to OpenSea collection to setup the royalties I am asked to sign a transaction and to pay a fee. This never happened before, is this a new way of doing things or is it something wrong with my contract?

image
image1130×534 43.4 KB

Thanks.