I woke up early this morning to get some work done before a call and suddenly my local dev environment stopped working without warning and with seemingly no reason. The root issue was that MySQL wouldn’t work,
/usr/local/opt/openssl/lib/libssl.1.0.0.dylib was not loading.
TL;DR: This may have been related to some automatic cleanup on Homebrew’s part. But regardless, a simple restart sorted it. If this happens again and restarting doesn’t sort it, try uninstalling and reinstalling MySQL.
The rest of the detail is below for posterity if I run in to this in the future.