UI still responds when application not responding showing on dock

The user reports one issue about my application does not responding.

When he right clicks my application icon on Mac dock, it shows "Applicaiton not responding" , but when he click on the buttons, input box or switch windows of my application UI, it works well, which mean my application is not really stuck.

Does anyone ever see such "FAKE" not responding issue happen ? and what's the reason?

He is on MacOS 12.4.0