Deprecated function: explode()

Steps to reproduce

Using the fresh installation repice.
Drupal 10.3.6
PHP 8.3.16

Saving a node will throw a deprecated error.
```Deprecated function: explode(): Passing null to parameter #2 ($string) of type string is deprecated in _provus_preprocess_group() (line 562 of profiles/provus/modules/custom/provus_core/provus_blocks/provus_blocks.module).```