Google has FLoC'ed up
FLoC is Google's newly pitched idea for tracking users online. I will not be going into details here, so I recommend you read EFF's article on FLoC for the necessary background information.
According to the specification websites will be able to opt-out of the proposed FLoC system by adding
Permissions-Policy: interest-cohort=() in their response header.
However, I will not be adding the line to any of my websites.
Why? I simply think it should not my job as a web developer to protect users from their own webbrowser that is collecting data on them. Adding this line to your HTTP Headers means you are complying with how Google wants to run the web.
I urge other web developers to not add this response header to their websites, but instead make a pop-up informing your users about FLoC and asking them to install a non-FLoC-enabled browser, such as LibreWolf or GNU IceCat