at any point they could have voted for an amendment to pause legislation given the current economic crisis.

Not in practice. Only the government can introduce such a law directly, not Labour or the other parties. Labour might have been able to attach such an amendment to some other bill, but that would rely on the Speaker selecting it, which he would be unlikely to do unless it was specifically about the bill. He would probably not have allowed it, for example, as an amendment to the Internal Market bill.

Now the bill has passed (for all practical purposes) we need to build from where we are, not where we could have been in other circumstances.