When setting a validation like:

/**
 * @Assert\Regex("/^\d+/")
 */
public $phone_number;

it generate an input text with the same pattern /^\d+/. Unfortunate, that pattern is not valid with HTML5 (should be ^\d+).. I recommend updating the pattern to be HTML5 compatible then on validate form convert it into PHP preg_match which is pretty much adding the / to the start and end of the pattern string.

What do you guy's think?