A guest still has a real game account
The game creates a guest identity for the current installation so your wallet and owned items can be associated with an account. Guest does not mean that Coins can be safely discarded. Write down any support reference the game offers and keep the installation while investigating account problems.
Avoid destructive troubleshooting
Clearing all Android app data, uninstalling or switching phones can remove the credentials needed to access an unsaved guest account. Closing and reopening the app is different from deleting its storage. Do not follow an unofficial instruction to wipe data just because a balance or connection is temporarily unavailable.
Save before an important change
Use Save with Play Games in Settings and confirm completion before reinstalling or replacing a device. If saving fails, keep the existing app and contact support. An order receipt can help investigate a purchase, but it is not a promise that every lost guest account will be recoverable.