I checked and is true that is enabled by default. The "Learn more" link on the setting lands here:

>PPA is enabled in Firefox starting in version 128. A small number of sites are going to test this and provide feedback to inform our standardization plans, and help us understand if this is likely to gain traction. PPA can be disabled in Firefox settings.

https://support.mozilla.org/es/kb/privacy-preserving-attribu...