No, when using a Firefox Account (FxA) once a Login is deleted from one device and that deletion is propagated to another device the Logoin is gone. No backups are saved by Sync or by the Firefox installation, but if you ever did a Refresh of the Profile and still have the Old Firefox Data folder sitting on your desktop you might be able to "restore" the two Logins files that contain your UserNames & Passwords (three files if you were using the Master Password feature in Firefox).

BTW, there is no primary / secondary device for Sync, they all carry equal weight with the Sync server and Firefox Accounts system.

If you use the Time Machine or other backup then try to restore file(s) from this backup.

• https://www.apple.com/support/timemachine/

For the passwords you need logins.json and key4.db.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Location used for the main profile that keeps your personal data (Root Directory on about:profiles).

• ~/Library/Application Support/Firefox/Profiles/<profile>/

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/Profiles