Windows 10 (version 1709+) and Windows Server (version 1803+) come with a security feature named Exploit protection. Exploit protection includes a number of mitigations from the Enhanced Mitigation Experience Toolkit (EMET) which reached end of support on July 31st, 2018.
While you can apply those mitigations to Firefox (i.e. firefox.exe), Mozilla recommends keeping the default settings of Exploit protection for firefox.exe. Since Microsoft can change the mitigation techniques at anytime, you may experience compatibility issues such as startup or sudden crashes or loss of functionality if you were to update from a working version.