Its when one or more of the tunnel connections is down but not all of them. it will have failed over to a different connection so its not down, just degraded
"New customers get new Rate Limiting by default while existing customers will be able to run both products in parallel: new and previous version."
"Existing customers will be granted the same amount of rules in the new, unmetered, system as the rules they’re currently using in the previous version (as of September 20, 2022). For example, if you are a Business customer with nine active rules in the previous version, you will get nine rules in the new system as well."
"In the future, the previous version of Rate Limiting will be deprecated, however we will give plenty of time to self-migrate rules."