With the release of Firefox 62, Mozilla also stops providing support to Firefox 52 ESR, which is the latest version for those still using this ancient operating system. Firefox 62 comes with support for CSS variable fonts and shapes, dark mode automatically enabled for macOS users, improved scrolling performance in Android, and more.
https://www.notebookcheck.net/Firefox-62-now-available-for-download-Mozilla-no-longer-supports-Windows-XP.328928.0.html