Getting this:
Deprecated function: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in custom_body_class_node_special_character_form_validate() (line 121 of modules/contrib/custom_body_class/custom_body_class.module).
Install the Custom Body Class module and use it.
Add NULL checks to vars before passing to preg_match()
2.0
Code
The issue particularly affects sites running on PHP version 8.2.0 or later.
I've applied the attached patch and tested this. The reported warning is no longer triggered.
Marking this as RTBC.