In one specific linguistic context. In others, 11:00 for 23:00 is perfectly fine and expected. Yes, it is ambiguous; no, it is not “lying”.
No, in all of them, including the 12 hour time default places. That’s what the “AM” or “PM” is for; if it isn’t there then it indicates it is 24 hour time regardless of the number displayed.
They use 24 hour time in most contexts, but often use 12 hour time informally and the actual time is understood in context. You might not believe it, but this happens.
It is, in fact, not unreasonable to ask for an option to format time in 12 hours without letters after. (I am not saying the author should do it; they are the one to choose what to do in their free time).
Settings like date and time formatting and physical units should ideally be changed by the user. You cannot expect a single setting to work all the time.
(Also, for what it's worth, you're objectively incorrect about it being lying; time is measured in 12 hour cycles in most locales, with further bits of information for time zone, before/after noon, day, month, and year. 23:00 is still "ambiguous", missing almost as much of that context, but it's not "lying" if you have the required context)