Comment by schnable

This is a bad idea. But in the same spirit, a bad but less bad idea: require the user to actively enable the deprecated feature via config or something, but have a known schedule to eventually expire it (with a hard error, not randomly incorrect data) and force the user to re-enable it. Causes some pain but not random, hard to track down bug. More like dealing with expiring certs - eventually, the user will want a permanent fix.