Error: Object of class Drupal\node\Entity\Node could not be converted to string

Problem/Motivation

When an administrator visits a node, they encounter the error "The website encountered an unexpected error. Try again later."

Normal users can access the node page without any problems.
When I disable "Data field" module, the problem disappears and the admin can access the node page, too.

Any idea, please ? Thanks

Here's the dblog record.

Error: Object of class Drupal\node\Entity\Node could not be converted to string in Drupal\Component\Render\HtmlEscapedText->__construct() (line 31 of /var/www/html/d11site/web/core/lib/Drupal/Component/Render/HtmlEscapedText.php).