Chrome inspector shows the email. But it is not displayed if you view the source in your browser.

Ok. Two screenshots of page source code (not inspector):

Joomla 4:

Joomla 5:

I can see from both of those screenshots that you are using a template override.

These are screenshots without any template override

Joomla 4

Joomla 5

@Scrabble96 can you check the console, if there is a javascript error?

No JS errors.

You are using template overrides as I have already shown!!

Ok. [I can't really see your images any bigger as when I click on them I just get a blank page with the URL https://private-user-images.githubusercontent.com/1296369/30... etc. Edit: Can't see mine, either. Not sure if it's a Firefox thing.]

I tracked it down. The difference was that I had this in my article default.php code:

          <?php echo $this->item->introtext; ?>
          <?php echo $this->item->fulltext; ?>

and the new version has this:

        <?php echo $this->item->text; ?>

Somehow I'd missed that when checking file updates.

          <?php echo $this->item->introtext; ?>
          <?php echo $this->item->fulltext; ?>

Yes that is your override and it is why it is breaking. fulltext does not process plugins. Only introtext and text do that. That is true for joomla 4 and joomla 5

But the good news is that I made a pr yesterday that fixes that

Great. Thanks.