This is showing up in the backend on my site. Looks like compatibility issue with PHP 8.1
Deprecated: DateTimeImmutable::createFromFormat(): Passing null to parameter #2 ($datetime) of type string is deprecated in /home/vpbyzrt/public_html/wp-content/plugins/meta-box/inc/fields/datetime.php on line 215
Do you know how to reproduce the issue with clear steps? If so, please share the steps with me.
In the meantime, I'm also going to escalate the issue to the development team to check and improve the code to prevent the error message from appearing again.