A player tag is an ID our team uses internally to identify a player account and was used when our team needed to check on issues related to a player's account. However, we have stopped using the Player Tag and players can provide their game's support ID when they are requesting assistance from our player support team.
The player tag only shows the status of a player's account and is not used to save the game progress. The player tag will display different IDs depending if a players is connected to an account. If your player tag displays Guest, then your account is not linked to an account and the data is saved to your phone. To save the game progress, players need to connect the game to a service like Facebook, Google, or Apple. The player tag changes when a player has connected their game to a service like Facebook, Google, or Apple.