To reproduce this issue, we have used a custom template https://squidex.github.io/squidex-samples/editors/country-selector.html.
We have created two stages Draft and published (prevent updates is checked)
When we are moving content from draft to published stage editor.onDisabled(callback) is not getting triggered. Also, even if we reload the content in the published stage, the custom editor is not getting disabled. I have tested this on https://cloud.squidex.io/.