@shakil_tcs - Mozilla uses trademark restrictions on the firefox logo to forbid any sort of sale/bundling for payment of the unmodified software, even if it is made clear that what is being sold is unmodified firefox, denying freedom 2 in some cases (although it is reasonable to require that a logo is removed for resale of modified software provided that changing the logo is trivial).
- Firefox by default recommends in the "new tab" page several websites full of malicious proprietary JavaScript and if the user clicks on any of them, firefox automatically and silently executes such malicious software.
- Firefox implements "Encrypted Media Extensions" digital handcuffs and doesn't adequately advise the user what is being done - it just pops up a box that says to play the video on the page, or not.
- Google is the default search engine and google search no longer works without malicious proprietary JavaScript.
- Firefox recommends proprietary extensions without saying they are proprietary.
- There is default spying, refereed to as "analytics".
- Which websites the user visits is reported to google via "google safebrowing".

Some of these issues alone don't make software proprietary, but the combination of all of these clearly make firefox proprietary software.

As always, when there is free source code, someone goes and takes any antifeatures out and there are free soft-forks like GNU icecat, Abrowser and Tor Browser.