Resolved
This incident is resolved.
Retroactive
Some users were unable to provision additional Performance-L dynos for their apps or first Performance-L dynos for new apps. This also affected Heroku CI test runs where the test run formation was configured to use Performance-L dynos. Affected test runs would manifest as one or more test nodes failing to start and timing out after two hours with no output. Users would not have been billed for these provisions, either.