Wow, even Whonix qubes are leaking dom0 time zone.
That was I said before, Qubes OS has no privacy (because by design it values only security), even whonix is not helping if we are not talking about web-browsing.
P.S. About telegram: there is a web version, and it works well, because Telegram has NO proper end-to-end encryption. Web version is additionally sandbox by browser and will be quite private running in whonix qube.
Do you mean disposable app qube based on disposable Whonix Workstation or disposable Whonix Workstation template itself? If to enter this command in any Whonix based app qube (including disposable app qube based on Whonix Workation disposable template) it shows only UTC time, not your local. Unless there is something wrong configured in your OS. And why to perform this operation in disposable template itself if it should have no internet connection? Only app qubes connecting to Internet.
Calm down! It is not. Check by yourself. This dude either misunderstood something or wrong configured his OS.
What does qubesdb-read /qubes-timezone output for you in whonix workstation?
You have already been told about javascript about which you can not know anything.
Are you replying him or me?
Maybe you have UTC timezone in dom0?
You can use local web version with known javascript files.
No. Would I say all this if I had UTC in dom0? 
Why are you asking? Enter command that he wrote in any Whonix based app qube’s terminal. Does it show your real time zone? In my case - no.
I mean this command: ```
timedatectl
You. He (them) already told that Qubes OS reveals their timezone even in whonix qube.
What’s the output of this command in dom0 terminal for you? Is it UTC?
date +%Z
So you checked and got the same result as he? In app qube?
NO! BIG F%%%ING “NO”!!! Do I not see what time shows my OS on the panel?
I have UTC in dom0, no way to check it. I have it that way exactly due to this Qubes OS privacy issue, that all, even very untrusted, qubes can grab the timezone (and thus approximated location) without any permissions.
So, my hack-solution is to set UTC in dom0 and in qubes, that I want to have different timezone, set iy in their /rw/config/rc.local script that is applied on qube boot.
When you change the timezone in the xfce panel clock plugin it’s not changing the system timezone and only changing the time displayed by this plugin.
I HAVE NOT UTC in dom0 and have no time leaks in Whonix app qubes! So you better change it in dom0 and check.
I used command you gave and it shows my local time that’s why I’m saying that it’s not UTC.
Then I don’t know why do you have UTC in whonix:
Do you mean template or app qube? Why should I enter this in template if templates have no internet connection? I used timedatectl in Whonix based app qubes and it shows only UTC time. Not my local.
Yes, that what I advise to use. Set timezone to UTC in dom0 and change xfce panel clock widget settings to at least look like you have some different local time.
Otherwise all qubes (at least regular ones) know your timezone (kind of location).