The subscription/updated webhook now includes a previous object alongside the current state, so you can see exactly what a subscription looked like before the change was applied.

This is especially useful if you run automations on subscription events but don't maintain your own database. You can now detect what changed and trigger the right downstream action without storing or comparing historical states yourself. The previous object is available for line actions (swaps, quantity updates, product add or remove), discount additions and removals, and billing or delivery policy updates.