[BUG] Issue with PREMIUMUUID being used instead of normal UUID after enabling /premium

[mjiangmc]

Describe the bug
When online-mode = true is enabled in the velocity.toml configuration, if a player uses the /premium command to enable premium authentication, the system incorrectly uses the PREMIUMUUID from the database instead of the regular UUID. This issue did not exist previously and appeared unexpectedly, causing data loss for some players due to the UUID change.

To Reproduce
Steps to reproduce the behavior:

1. Set online-mode = true in velocity.toml.
2. A player executes /premium in-game to enable premium authentication.
3. Upon the next login, the system reads PREMIUMUUID from the database instead of UUID, causing the player to log in as a completely new identity (leading to data loss or failure to load original UUID data).

Expected behavior
Even when a player enables /premium and Velocity is set to online-mode = true, the server should continue to use the original UUID (or correctly maintain the previous UUID mapping mechanism) rather than abruptly switching to PREMIUMUUID and causing data loss.

Server Info (please complete the following information):

• All Limbo plugins versions:
• Latest version compiled from GitHub Actions (Development Build / Latest Artifact)

Additional context
This issue started occurring suddenly. Previously, the premium authentication and UUID loading worked flawlessly, and enabling /premium did not cause the player's UUID to switch to PREMIUMUUID. Please help investigate which recent update or change introduced this breaking UUID switching behavior.