Mozilla stops support for the upcoming version of Firefox Web Browser for macOS Mojave and earlier macOS Operating Systems. those won’t get major updates for Firefox Web Browser. but some security updates will update for this year. As Mozilla organisation release notes states that users can get updates up to ESR 115 version for firefox who running macOS 10.12, 10.13 and 10.14.
Mozilla will release latest version of Firefox 116 is set for August 2023. So, it will require minium macOS Catalina 10.15 or later. Mozilla explain about maintaining its web browser for obsolete macOS can become costly. and also dangerous for users. Firefox 115 will receive important security updates until september 2024.