Can you post such a module?
I wanted to test for plugins but I can't install a 3.x plugin on j4 because I get a Call to a member function clean() on null from
Undefined variable: pathObject in /Applications/MAMP/htdocs/installmulti/joomla40/libraries/src/Filesystem/File.php on line 472

Also tested after modifying that plugin to use J4 methods. Same result.

Ok, therefore I added the plugin manually and I discovered it Ok.
Language file is loaded fine.
Will try to find a module where the language files are only in its language folder to test your issue (on last j4.0-dev)

Strings are loaded OK in backend for a module.
Do you have the issue in backend as well as frontend?

@joeforjoomla where do you see untranslated strings?

@infograf768 please test #22771 if the upload works now.

@infograf768 @laoneo refer to this PR #22786 where i narrowed down the problem, probably due to the recently merged modules dispatcher

Set to "closed" on behalf of @Quy by The JTracker Application at issues.joomla.org/joomla-cms/22768

@joeforjoomla
You have not replied to my question.
Is the issue present in frontend too?
IN backend I could not reproduce your issue.

Please add here the zip of a module for which you have the issue as I could not reproduce it.

I again did a test:
I took off from the core language folder in admin the 2 files
en-GB.mod_multilangstatus.ini
en-GB.mod_multilangstatus.sys.ini

These 2 files are also present in the language folder of the module.
They ARE loaded OK, as can be seen in the debug below:

To test debug lang for site modules, one has first to apply this patch:
#22775

HMm, tested in frontend and the issue IS in frontend.
will test now #22786

See my comment #22786 (comment)