https://support.mozilla.org/en-US/kb/what-happened-firefox-s...
> Firefox Send has been discontinued as of September 17th, 2020. You will no longer be able to upload or receive files. We’d like to thank all of you who tried Firefox Send.
> We started Firefox Send as a way for you to share files safely and easily from any browser. Unfortunately, some abusive users were beginning to use Firefox Send to ship malware and conduct phishing attacks. When this problem was reported, we stopped the service. Please see the Mozilla Blog for more details on why this service was discontinued.