OK, so after checking more, need to add these styles to theme style file.
I copy these classes from 9.3.3
.woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) #respond input#submit, .woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) a.button, .woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) button.button, .woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) input.button, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce #respond input#submit, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce a.button, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce button.button, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce input.button {
font-size: 100%;
margin: 0;
line-height: 1;
cursor: pointer;
position: relative;
text-decoration: none;
overflow: visible;
padding: .618em 1em;
font-weight: 700;
border-radius: 3px;
left: auto;
color: #515151;
background-color: #e9e6ed;
border: 0;
display: inline-block;
background-image: none;
box-shadow: none;
text-shadow: none
}
.woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) #respond input#submit.alt, .woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) a.button.alt, .woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) button.button.alt, .woocommerce:where(body:not(.woocommerce-block-theme-has-button-styles)) input.button.alt, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce #respond input#submit.alt, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce a.button.alt, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce button.button.alt, :where(body:not(.woocommerce-block-theme-has-button-styles)) .woocommerce input.button.alt {
background-color: #7f54b3;
color: #fff;
-webkit-font-smoothing: antialiased
}
There are the specific styles that need to add to make it work.
I isolated it to these classes.
The question is if it is a workaround or a final solution.
Is this change in WooCommerce is considered as a bug?