Mozilla released Firefox Version 126.96.36.199 for Windows desktop, Mac, Linux and Android OS. Mozilla Firefox Version 188.8.131.52 added patches for 13 different security advisories, user-experience features and some new security improvements such as Opportunistic Encryption (OE) for servers and websites that support HTTP/2 AltSvc.
Opportunistic Encryption (OE) allows Firefox browser to encrypt traffic over plaintext HTTP connection without any need to authenticate it. Opportunistic Encryption (OE) will help you to create, not complete, but some confidentiality from attackers to eavesdrop on connection. So Opportunistic encryption can be implemented with very minimal changes to existing IPsec implementation.
In addition to Opportunistic Encryption, Firefox Version 37 also introduces Heartbeat user rating system, which will gather feedback from users of its browser. The response from its users will be of great help to Firefox developers to feed the needs of its users into future Firefox releases.
Refer: Mozilla Firefox version 184.108.40.206 Release Note