Black Hole

I know of some users that simply used a new gift code to unlock their account again. Also you could upgrade your old unpaid account anytime.

No, since no profile is found for revoked payments. These users once had a paid account and these uuids were returned: luisfritzi a09875e4-4eff-464d-8ddd-ab337995eb89 Juli180702 de506882-4d36-4143-acb3-2ebc656ff970 michiundsimon 4604c573-273d-4d51-8c66-ef1b1c23891c bsg4ever95 19e0ccc2-6f3e-42bd-aad7-7dea850f1740 RocketFlying...

This seems to be designed this way: https://github.com/PaperMC/Waterfall/blob/master/BungeeCord-Patches/0024-Validate-that-chat-messages-are-non-blank.patch

Affects Paper running on 1.21.8, too.