There WAS an issue described in https://github.com/serlo/moodle-mod_serlo/issues/9 :
the plugin uses hard-coded text without the ability to change/translate language strings.
All user-facing strings should be defined in the language file and displayed using the get_string() function.
https://moodledev.io/general/community/plugincontribution/checklist#strings
But the English language strings are in the GitHub code and inside the ZIP package for download.
And in line 35 think there is a string concatenation... which I think might be the problem...
the plugin uses hard-coded text without the ability to change/translate language strings.
All user-facing strings should be defined in the language file and displayed using the get_string() function.
https://moodledev.io/general/community/plugincontribution/checklist#strings
But the English language strings are in the GitHub code and inside the ZIP package for download.
And in line 35 think there is a string concatenation... which I think might be the problem...
$string['firefox_warning'] = 'There are some problems with Firefox at the moment. ' .
'Please use a Chromium based browser like Chrome, Brave or Opera for a better experience.';
'Please use a Chromium based browser like Chrome, Brave or Opera for a better experience.';
BUT the GitHub code does not have this concatenated string...
I wrote an issue at https://github.com/serlo/moodle-mod_serlo/issues/15