COS for Firefox was removed from Mozilla website?
Can we get any update on this?
No it was just re-named to online security pro which causes the link to change https://addons.mozilla.org/en-US/firefox/addon/online-security-pro they just haven’t announced the change here at the forums but the link is updated on the Comodo Online Security | Web Filtering Extension for Google Chrome page. I’ll update the OP with the new link.
Thank you 
COS (named COS Pro beginning with version 2.0) has been updated several times since 1.2.45944.37 was released.
Version 2.9.0.83
Released 3 Sep 2019 - 300.86 kB
Works with firefox 53.0 and later
- performance improvements
Source code released under Comodo End User License
Version 2.8.0.82
Released 1 Aug 2019 - 289.79 kB
Works with firefox 53.0 and later
- Performance improvements
Source code released under Comodo End User License
Version 2.7.0.81
Released 9 Jul 2019 - 289.79 kB
Works with firefox 53.0 and later
- Performance improvements
Source code released under Comodo End User License
Version 2.6.0.78
Released 27 Jun 2019 - 289.02 kB
Works with firefox 53.0 and later
- Performance improvements
Source code released under Comodo End User License
Version 2.5.0.75
Released 10 Jun 2019 - 284.93 kB
Works with firefox 53.0 and later
- Performance improvements
Source code released under Comodo End User License
Version 2.4.0.74
Released 28 May 2019 - 284.94 kB
Works with firefox 53.0 and later
- Block page bugfix
Source code released under Comodo End User License
Version 2.3.0.72
Released 30 Apr 2019 - 295.34 kB
Works with firefox 53.0 and later
- Security updates implemented
- Performance improvements
Source code released under Comodo End User License
Version 2.2.0.70
Released 13 Mar 2019 - 284.31 kB
Works with firefox 53.0 and later
- Notification updates
- Design issues fixed
Source code released under Comodo End User License
Version 2.1.0.68
Released 1 Mar 2019 - 284.83 kB
Works with firefox 53.0 and later
- Local alert page added
- Performance improvements implemented
- Icon based notification logic addd
Source code released under Comodo End User License
Version 2.0.0.66
Released 20 Feb 2019 - 251.22 kB
Works with firefox 53.0 and later
- Performance improvements
- New algorithms implementation at server side
- Advanced protection implementation
Source code released under Comodo End User License
Version 2.0.0.64
Released 22 Jan 2019 - 251.16 kB
Works with firefox 53.0 and later
- Notification issue solved
- Performance improvements
Source code released under Comodo End User License
Version 2.0.0.62
Released 16 Jan 2019 - 248.99 kB
Works with firefox 53.0 and later
- New design and easy-to-use concept
- Security improvements
- Notification section added
Source code released under Comodo End User License
Version 2.0.0.60
Released 27 Dec 2018 - 225.81 kB
Works with firefox 53.0 and later
- Performance issues solved
- High security features added
Source code released under Comodo End User License
Version 2.0.0.57
Released 17 Dec 2018 - 225.77 kB
Works with firefox 53.0 and later
We improved the Comodo Online Security and make it more professional for our users. We did:
- Performance improvements
- New pop-up menu with easy-to-use options
- Icon changed
- Extension name changed
Source code released under Comodo End User License
Version 1.2.48716.43
Released 14 May 2018 - 233.46 kB
Works with firefox 53.0 and later, android 53.0 and later
- Drop down menu from toolbar icon has fixed font. So look and feel should be same across Operating Systems.
- There is a new ‘Feedback’ link in About section taking user to Comodo forums for submitting feedback.
Source code released under Comodo End User License
Version 1.2.48162.42
Released 27 Apr 2018 - 233.35 kB
Works with firefox 53.0 and later, android 53.0 and later
- Modified plugin based on Mozilla’s review
Source code released under Comodo End User License
Source: https://addons.mozilla.org/firefox/addon/online-security-pro/versions/