As per the title, tmgmt_available_languages() supports being passed an excluded languages array but every call to it isn't populated.
I took out the parameter as it didn't seem sensible to keep passing it in ... instead it's just pulled out of the config factory within the function itself. I didn't bother with a test for this as I felt like it'd just be testing PHP functionality? But I'm happy to add some kind of test if someone feels that in_array() really needs a test applied to it?...
Needs review
1.0
Core
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.
6 YEARS ...
Well, I guess you could do this now:
$languages = array_map(fn ($language) => $language->getName(), $this->languageManager->getLanguages());
It doesn't seem like it matters though, if they haven't merged it yet - unlikely they'll merge it in the next 6 years either.