Announcing a removal date without instrumentation means the date arrives and nobody can say whether removing it is safe.
the sequence that works:
1 instrument usage per version, per client
2 announce header, changelog, and email
3 wait and watch the number fall
4 contact the ones that have not moved
5 disable for a day, deliberately, and watch
6 remove after 30 days at zero
step 5 is the one people skip, and it is the one that
finds the client nobody instrumented.The brownout — disabling deliberately for a short window — is the step that converts uncertainty into a list of phone calls. It has to be announced and it has to be short, and it reliably finds the integration that authenticates as a user nobody attributed to a client.