In March, Square Enix will introduce linking FFXIV accounts and Steam accounts for Steam users' extra security.
Previously, FFXIV users have been able to log into their Square Enix account from any instance of Steam. Now, Square Enix is adding a layer of security for Steam users to prevent their accounts from being used across multiple Steam accounts.
Introducing Steam Version Account Linking (Source)
As part of ongoing efforts to further enhance account security and bolster fraud prevention measures, we will be implementing an additional account verification and login confirmation process for FINAL FANTASY XIV Steam version service account holders. Users can verify their account type by logging into the Mog Station and selecting the “Service Account Status” menu where Steam service account holders will see a “(Steam)” notation.
Currently, Steam version service accounts can be used after FINAL FANTASY XIV has been launched from any instance of the Steam software.
Starting in early March 2022, users who log in using a Steam version service account will be prompted to perform a one-time link of their Steam account to their Square Enix account. From then on, the Square Enix account will need to match the Steam account that launches the FINAL FANTASY XIV software. This change will require the FINAL FANTASY XIV software to be launched from the user’s Steam library. Additionally, once the account link has been performed, users will need to utilize the new launcher layout introduced with Patch 6.0. If using the “Original Launcher Layout” setting in the launcher Config menu, please switch to the “New Launcher Layout.”
To link accounts, the Steam account must possess a FINAL FANTASY XIV license that matches that found on the target Square Enix account/FINAL FANTASY XIV service account (e.g., the Free Trial version or the full game version). You can verify the FINAL FANTASY XIV licenses on your Steam account by clicking on your Steam display name, selecting “Account details,” then “View licenses and product key activations” found under Store & Purchase History.
If your Steam account no longer has a FINAL FANTASY XIV license, or you no longer have access to the Steam account that contains the license, please contact Steam for assistance. (https://help.steampowered.com/)
Source: News Latest Topics https://www.icy-veins.com/forums/topic/64145-ffxiv-introduces-steam-version-account-linking/