Good afternoon. After syncing the browser and phone, tabs from the computer are not sent to the ios device
make sure that you are signed in on both devices. You might try a manual sync both on your desktop and iPhone. Use the "Sync now" option by clicking on your profile picture in Firefox on Desktop. On iOS, open the menu ≡ and click the sync button displayed next to your Firefox user name.
Your synced tabs should appear under "Your Library" by opening a new tab on iOS. https://support.mozilla.org/en-US/kb/where-are-my-synced-tabs-firefox-ios