Steps to reproduce the issue

I have a plugin using onContentPrepare.
Create two modules:

1. Articles
2. Articles - Newsflash (Legacy)

Module 2 (from Articles - Newsflash (Legacy)) works perfect.
Module 1 (from the new Articles) does not trigger onContentPrepare

Expected result

Both modules should display the same result

Actual result

Module 1 does not process the onContentPrepare.

System information (as much as possible)

Both Joomla 5 and 6 (alpha)

Additional comments

Solution:
Add in \modules\mod_articles\src\Helper\ArticlesHelper.php after line 343:
'onContentPrepare' => new Content\ContentPrepareEvent('onContentPrepare', $contentEventArguments),
above the line:
'afterDisplayTitle' => new Content\AfterTitleEvent('onContentAfterTitle', $contentEventArguments),

This is consistent with the code in:
\modules\mod_articles_news\src\Helper\ArticlesNewsHelper.php