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As you could see on attached screenshot there are no links to the past stages at all on payment page.
Perhaps this is a problem with a particular payment module? I've tried it with the test module (using Commerce Kickstart 1) and the links do not get deactivated on the Payment page. Also, there are several "LiqPay" sandboxes around so you may want to see if those modules do anything to alter the permissions or checkout flow. Feel free to reopen if this is still a problem and you have a specific set of instructions to reproduce.
To chime in: I'm 99% sure the payment gateway module needs to provide a back button with a specific token, otherwise the state defines how an order can move in checkout.
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