Hello,

So we have confirmed the issue from our Test Site, the default Thank You page is appearing fine. Here you can check our Test Site: https://blackpearlspro.com/woodmart_support/checkout/order-received/11498/?key=wc_order_PcF3QLTjGpsfy

So, this clears the fact that the issue is not at the Theme level.

It seems that you are currently using Staging platform through a third party which is why it is not working correctly on your Site because some of the Customers faced this in their Staging platform but not in actual Development platform. So, can you please once try it on a real Live Domain other than the Staging one and then check back the issue again. Hopefully, you won’t find the issue again.

Best Regards