Make time zone specification optional for the whole app
I don't really know of any app that allows you to specify the time zone in addition to the time... For me personally, specifying the time zone of a time entry has no relevance - and I think the same is true for many other users.
Therefore, I would like to make the following suggestion: The radio button that allows the time zone to be specified is only displayed in the app if the user explicitly wants it to be. And this can be set in the settings: