@Leo The Place Order loader is on the top of the page, but that is not helpful for customers when the Place Order button is at the bottom of the page. There is no Visual Cue for the customer that the order is being processed.
The default WooCommerce setup is to have the loader in the center of the page with a transparent white overlay. Can you add that to your WooCommerce template/CSS? I think this would help with the UX.
But the default WooCommerce setup does add a transparent white (maybe 70% opacity) overlay above the checkout section during processing. Is that something we would have to add back in as custom CSS, or can you add that to your theme/plugins Template/CSS files?