Mozilla has yet to make the decision on whether to continue with updates past Firefox 115.21.0esr in March. However even if they do it may only be for say another six months. Currently Firefox is the only web browser that still supports the eol macOS 10.12, 10.13, 10.14 so there are no other options, especially with Chrome/Chromium based browsers. Any Firefox forks that was using the older Fx 115esr codebase will be affected also when Fx 115esr ends. There is the SeaMonkey suite that may be an option if they continue to support macOS 10.12, 10.13, 10.14 and not go to macOS 10.15 or later.