Action required: Use "checkout.order_id" on the Thank You page

I have just got an email mentioned in the pictures attached. Please help me resolve the issue

A similar post was posted before with a solution. Here was that post:
Solved: Got email from Shopify - “order.{anything}” replace with “checkout.order_id” in additional…

Hope this helped!

Yes @PaulMartin_1 , i could not understand this, need more clearance about it