No UTF-8 in templates

In my application I have a coulple of templates/views. Now my problem is, that in one single template the UTF-8 is not used.
Does anyone have an idea what I can douple check respectively what the reasons can be? Currently I have absolutely no clue.
In the total application excepting the one page, UTF-8 works fine.

And yes, the <meta charset="UTF-8"> is added to the html-head-tag.

Please provide a reproduction. You can start with the template here:

You could try divide-and-conquer to find what part of the file breaks, might be just one weird character.