Hi Zdeněk,
I am not able to replicate this issue locally(http://take.ms/RchXD). Perhaps you can provide us the backend and ftp access to the site experiencing this issue at http://stackideas.com/dashboard/site so we can help you check this out.

Access data is Arlex Wong.
Or do I have to send it to you again?

Hey Zdeněk,
It would be best if you can fill in the site details here: http://stackideas.com/dashboard/site so that we do not have to refer to past tickets for the information.
As for your issue, I could not access your ftp. Can you check and make sure there are no spaces in the following file? Refer screenshot.
JoomlaFolder/modules/mod_easydiscuss_quickquestion/tmpl/default.php
http://take.ms/BtV41

Our current office IP: 175.139.129.82

I added your IP to the list of enabled ones, which should work for you

Hey Zdeněk,
I am able to access your ftp now.
It seems the plugin System - Aixeena Clean Code along with the setting Use Clean PHP Function(http://take.ms/QFfm6) is causing the placeholder to not show.
Since I'm not familiar with this plugin, perhaps you can consult the plugin provider so they can explain more on the issue?

Thank you very much.

You're most welcome Zdeněk.
Regards.