Google was already in the middle of a class-action lawsuit regarding the incognito mode, where they were accused of tracking user activity. And, they agreed to settle the lawsuit.
To conclude that and move on, they will have to make the necessary changes to prevent another lawsuit against them.
Honestly, this article is pretty bad at explaining the problem here. It’s clear that other websites will try to track you, but the important part of this incognito drama is this:
https://arstechnica.com/tech-policy/2023/12/google-agrees-to-settle-in-chrome-incognito-mode-class-action-lawsuit/