When typing in an input (textarea, input tag, editable, …) which is itself placed inside of a custom html element, the hotkey is still fired. That's because the isFormField handler checks only the target element, which is this case is the custom element. It should instead use the explicitOriginalTarget property, since that contains the actual input element.

Here's a minimal reproduction: https://jsfiddle.net/zm7etdh3/