We use the session cookie to maintain state between a front end and the back end running Rails. The front end and back end are typically running on different hosts. The problem this introduces is that this cookie is a cross site cookie, and browsers are eliminating support for these. The browser vendors are providing a replacement. Cross site cookies will be allowed, so long as they are partitioned. A partitioned cookie is only active for the top level site for which it was originally set. To enable this, one has to be able to set the partitioned flag. See https://developers.google.com/privacy-sandbox/3pcd/chips . This doesn't work for session cookies today, at least in the version of Rails (7.0.4.2) I am running.