HubSpot allows marketers to create custom styled CTA buttons. This can be a problem if you have a large team who may not know how to follow brand guidelines. This creative freedom can make buttons look inconsistent across your website. You could educate all of your users to never create custom styles. Or you could add this code to your theme or template to strip out any inline styles overriding your default button styles.
$( window ).load(function() {
$('.hs_cos_wrapper_type_cta .btn').removeAttr('id');
});