Simon Willison’s Weblog

In 2021 we [the Mozilla engineering team] found “samesite=lax by default” isn’t shippable without what you call the “two minute twist” - you risk breaking a lot of websites. If you have that kind of two-minute exception, a lot of exploits that were supposed to be prevented remain possible.

When we tried rolling it out, we had to deal with a lot of broken websites: Debugging cookie behavior in website backends is nontrivial from a browser.

Firefox also had a prototype of what I believe is a better protection (including additional privacy benefits) already underway (called total cookie protection).

Given all of this, we paused samesite lax by default development in favor of this.

— Frederik Braun