Opting out of Google's New tracking Method – FLoC
Luckily, this is quite easy – for now.
Just add the “Permissions-Policy: interest-cohort=()” header in your webserver. This can be done as following:
In Apache (including .htaccess):
Header always set Permissions-Policy: interest-cohort=()
In Nginx
add_header Permissions-Policy: interest-cohort=()
That's it!
Edit: In January 2022, Google announced that they would abandon FLOC