Our use case is a Discovery Service - SeamlessAccess (SA). In this scenario the common flow is that the end user visits a Service Provider (SP) with the SA button embedded in an iframe, and upon clicking it, the user is sent to SA at the top level, where they can choose an Identity Provider (IdP). Ideally this choice, if stored in a cookie, would be available to SA embedded in the page of the SP, when the user returns to the SP. We are calling requestStorageAccess when the user clicks on the SA button embedded in an SP. The current behavior results in this UX:

• User visits SP with embedded SA iframe;
• User clicks on SA button and is sent to SA at the top level;
• User chooses an IdP, and SA stores the choice in the cookie;
• (...)
• User returns to SP, but the iframe cannot yet access the cookie;
• User clicks the SA button, and now requestStorageAccess prompts the user for access permission;
• On subsequent visits to the SP, the iframe can access the cookie.

Ideally, on the 2nd visit to the SP, the iframe would already be able to access the cookie. This would be possible if requestStorageAccess were not prevented, by the lack of a previous visit to SA at the top level, to ask for access permission on the 1st visit.