No, there are some meaningful differences in the Manifest v3 implementation in Firefox: https://blog.mozilla.org/addons/2022/05/18/manifest-v3-in-firefox-recap-

No, there are some meaningful differences in the Manifest v3 implementation in Firefox: https://blog.mozilla.org/addons/2022/05/18/manifest-v3-in-firefox-recap-next-steps/ https://blog.mozilla.org/addons/2022/05/18/manifest-v3-in-fi... One such difference (and not the least) is: > Mozilla will maintain support for blocking WebRequest in MV3. To maximize compatibility with other browsers, we will also ship support for declarativeNetRequest.