List of steps to reproduce (step by step, including full links if applicable):

• create a form with a mandatory combobox field :

{{{field|MyField|input type=combobox|values from category=MyCategory|mandatory}}}

• test the form by not entering any value in the combobox field

What happens?:
The creation or update of the page targeted by the form takes place despite the absence of a value in the combobox field.

What should have happened instead?:
The creation or update of the page targeted by the form should not be possible until a value has been entered in the combobox field.

Software version (if not a Wikimedia wiki), browser information, screenshots, other information, etc.:

• MW version: 1.37.2
• DB (MySQL etc.): 10.1.48-MariaDB
• PHP version: 7.4.27
• SMW version: 4.0.1
• SRF version: 4.0.1
• PF version: 5.3.4
• Browsers and versions (if applicable): Firefox 99.0 (64 bits)