PSA: Third-party cookie deprecation for 1% of Chrome Stable starting Q1 2024

[Rowan Merewood]

Hi blink-dev,

We posted a major Privacy Sandbox announcement on 2023/05/18:
https://privacysandbox.com/news/the-next-stages-of-privacy-sandbox-general-availability
https://developer.chrome.com/blog/shipping-privacy-sandbox/

As an FYI, here are the key points distilled for readers of this list:

- We are planning to provide two modes of Chrome-facilitated testing for sites to meaningfully preview working in a world without third-party cookies. We will send I2Ps for each of these.

Mode A: Ad techs can receive control and experiment labels on a portion of traffic and use these to conduct testing and experiments starting in Q4 2023.

Mode B: Chrome globally disables third-party cookies for up to 1% of all Chrome users starting in Q1 2024.

Note that Mode B will apply to all third-party cookies in that 1% population, and may impact user-facing functionality. If your sites rely on third-party cookie data, then we have a guide for understanding if CHIPS or First-Party Sets address your needs: https://developer.chrome.com/docs/privacy-sandbox/third-party-cookie-phase-out/ and an issue tracker for reporting affected sites: https://goo.gle/report-3pc-broken

- We'll be sending the I2S messages for Topics, Protected Audience, Attribution Reporting, Private Aggregation, Shared Storage, Fenced Frames soon targeting 115.

- We've got open issues on the Chrome-facilitated testing options here: https://github.com/GoogleChromeLabs/privacy-sandbox-dev-support/labels/chrome-testing and you can also raise additional questions there.