Steps to reproduce the issue

1. Create and save a contact by user 'One'
2. delete user 'One'
3. Open the contact created at step 1
4. click its versions-button

Expected result

No deprecated warning

Actual result

Deprecated: htmlspecialchars(): Passing null to parameter #1 ($string) of type string is deprecated in /mnt/data/vhosts/casite-1455743.cloudaccess.net/httpdocs/administrator/components/com_contenthistory/tmpl/history/modal.php on line 103

System information (as much as possible)

PHP Built On Linux lamp302.cloudaccess.net 3.10.0-962.3.2.lve1.5.81.el6h.x86_64 #1 SMP Wed May 31 12:07:35 UTC 2023 x86_64
Database Type mysql
Database Version 8.0.34-cll-lve
Database Collation utf8mb4_general_ci
Database Connection Collation utf8mb4_0900_ai_ci
Database Connection Encryption None
Database Server Supports Connection Encryption Yes
PHP Version 8.1.24
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 5.0.1 Stable [ Kuboresha ] 28-November-2023 16:00 GMT
Joomla Backward Compatibility Plugin Enabled (classes_aliases:"1", es5_assets:"1")
User Agent Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:120.0) Gecko/20100101 Firefox/120.0