https://support.mozilla.org/en-US/kb/firefox-users-windows-7-8-and-81-moving-extended-support You are on the Firefox '''115 ESR''' channel. It is currently at 115.21.0esr and will be updated till 115.27.0esr in August unless Mozilla extends updates again. Firefox 116.0 and later requires Windows 10, 11 to run. The older Firefox 115 ESR channel is being updated for Windows 7, 8, 8.1 (and macOS 10.12, 10.13, 10.14) OS users in mind. If you were thinking of the newer Firefox 128 ESR channel then it will not run on your Windows 8 as it requires Windows, 10, 11 to run.