After the update a new Placeholder is generated.
Link:
https://via.placeholder.com/600×900/6c757d/FFFFFF?text=not%20authorized%20`/var/www/vhosts/***h/httpdocs/wp-content/uploads/2021/06/REKLAMATIONSANZEIGE.pdf
Assuming, that the error message is on the image it would be
” not authorized `/var/www/vhosts/***/httpdocs/wp-content/uploads/2021/06/REKLAMATIONSANZEIGE.pdf” so it seems like a permission error.
Could you assist me in assigning the correct permission?