It should. [https://www.mozilla.org/firefox/83.0/releasenotes/ Firefox version 83] and higher support both Intel-based Macs (x86 architecture) and Apple devices with the new ARM-based CPU ([https://support.apple.com/HT211814 Apple Silicon]). Firefox 83 runs on new Apple Silicon devices by way of Apple's [https://support.apple.com/HT211861 Rosetta 2] emulation software and thus performance speeds may suffer. Version 84 beta is expected to run natively (not under emulation).