We found the problem. It doesn’t happen if you do the __() for example inside your function.php or in the root php file of a plugin. But as soon as you go inside a shortcode or another “ob” function environment you get silent ascii characters like:
!trpst#trp-gettext data-trpgettextoriginal=2022#!trpen#Publishing#!trpst#/trp-gettext#!trpen
In order to fix this we now use the offered trp_translate() instead but for that you need an extra private page where you list all your values. With that you can normally translate your words from your root language into any other language with TranslatePress as known.