Since this problem still exists in the latest Safari version (16.5.2) and we're having problems with this as well. I've added some details of our cookie problem when loading (rendered JavaScript) assets on https://bugs.webkit.org/show_bug.cgi?id=255524 It seems that any value in the SameSite attribute of the cookies causes this to happen. We could see that just 4 of the 7 cookies were kept during all requests and the other three get lost from time to time. Hoping for an official fix soon.