Bug: Submit buttons are always primary, ignoring the secondary type

Problem/Motivation

Drupal provides styling for submit buttons, to make secondary buttons, at least, like this:

$form['actions']['submit_secondary'] = [
  '#type' => 'submit',
  '#value' => t('Secondary action'),
  '#button_type' => 'secondary', 
];

But in the FlexiStyle Bootstrap theme, the buttons are always primary.

This is hardcoded in the theme https://git.drupalcode.org/project/flexistyle_bootstrap/-/blob/d441bc569...
<button{{ attributes.addClass('btn', 'btn-primary') }}>{{ attributes.value }}</button>{{ children }}
Please fix this and make the style follow the Drupal button type.