A human error caused an issue with the configuration of the add-ons reverse proxies at 12:18 UTC. MySQL dedicated add-ons were unavailable at this point, except for already open connections.
At 12:30 UTC, we found the cause of the issue.
At 12:32 UTC, the issue was fixed and we regenerated the reverse proxies configuration.
At 12:33 UTC, add-ons were available again.
We have put the necessary protections in place to prevent this from happening in the future.