I do think Firefox gets a degraded experience on some websites.

For example, Google Meet supports virtual video backgrounds and 3D face filters for Chromium based browsers.

And Google Search serves up an older results page design with fewer features to Firefox users. Someone has literally had to create a Firefox addon to make it pretend to be Chrome so it gets the modern results page.

I realise these are both Google-owned websites - but I don’t think it’s accurate to say that the average user isn’t going to come up across these differences.