I have the same issue.

We also have this issue on macOS 15 and Safari 18, 18.0.1 and 18.1. We have made a minimal example to reproduce the issue. https://www.icloud.com/iclouddrive/0bajlhnuQaG6T5NsFKXEB0U9Q#test%5Fcookies

I discovered the following comment in a relevant discussion: https://developer.apple.com/forums/thread/761323?answerId=827607022#827607022 By using the storeId, we were able to successfully retrieve the cookies. async function getAllCookies(name, url) { const stores = await browser.cookies.getAllCookieStores(); var cookies = [] for (const store of stores) { const cookieOfStore = await browser.cookies.getAll({ name, url, storeId: store.id }); cookies.push(...cookieOfStore); } return cookies; } await getAllCookies("geo", "https://apple.com");