Badge cannot remove 'bg-secondary' class after adding other bootstrap classes

[confettidc]

This is a (multiple allowed):

• bug

• enhancement

• feature-discussion (RFC)

• BootstrapUI Version: 4.0.0

• Bootstrap Framework Version: 5.1

• jQuery: 3.4.1

• Platform and Target: Nginx, CakePHP 4.2.6

What you did

I try use "bg-white" class instead of "bg-secondary" but seems the default class cannot be replaced:
<?php echo $this->Html->badge('xxx', ['class' => 'text-primary border-primary bg-white']); ?>

"bg-white" is one of default class defined in bootstrap:
https://getbootstrap.com/docs/5.1/utilities/background/#background-color

Expected Behavior

"bg-secondary" class should be removed, e.g.
<span class="text-primary border-primary bg-white badge">xxx</span>

Actual Behavior

"bg-secondary" class not removed, e.g.
<span class="text-primary border-primary bg-white badge bg-secondary">xxx</span>

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[ndm2]

I don't think I've ever used white, body or transparent for badges, or pretty much any other component, so I'm not sure whether the current behavior is correct/intentional.

Is there possibly a reason that those three colors aren't listed in the badge background colors docs, nor for any other component for that matter (with the exception of transparent for removing the background of cards)?