Am I reading this right? As far as I can see, the complaint seems to be that Google would be "tracking" people even if they browse in any browser's incognito mode.
Of course they do. If I open a private window in Firefox, and then login to Facebook, Instagram, Twitter, Reddit, or any other website, these websites can try to track me. How would any browser control what happens or doesn't happen on the server side of things?
These plaintiffs would be better off sueing the companies of these websites for ignoring privacy laws and continuing to add tracking scripts to their sites.
Yes, there are browsers that try to send as little personal information as possible, like the Tor Browser, but even that one can't disable a Facebook server's internal logging data - how could it? All modern browsers make it quite clear what their respective incognito mode does - and what it doesn't do.