Disabling Apple Intelligence suggestions in Messages...in a strange place

The actual way to disable these suggestions in Messages on MacOS:

In System Settings: Apple Intelligence & Siri, click the “About Siri, Dictation & Privacy…” button.

In the panel that opens, go to Messages. Turn off “Show Siri Suggestions in application”.

(When I turned this off, an already-generated suggestion in Messages continued to be shown to me in a chat thread. But new suggestions stopped being generated and shown.)

This kind of lack of attention to detail is getting maddening. What is happening at Apple?