I can see the whole point of the new dashboard: obfuscate, confuse, maximize billings with unanticipated charges, remove accountability, and breakage.
ALL credits expire. The initial free credit, three months after account creation. Then purchased ones after a year. There’s no system to even observe that credits are ensured a first-in-first-out so that your expiring credits aren’t the first used.
Lesson: buy credits in intervals like $40.01, $40.02 to identify them against further loss of context.