If your Product rate is not consistent in your Opportunity and Credit Proposal Disclosure merged template you need to check the Opportunity field entries.
When you run your Product Comparison search you will be shown Rates based on the Loan Amount and LVR that you use for your search.
The above example is $1,500,000 with an LVR of 75%
You will see those same Rates displayed in the Comparison itself according to the Loan Amount and LVR in the left hand panel.
When you then select a Product and 'Apply Product to Opportunity' it will be added to the Products section of the Opportunity. The rate in this example is now higher than in the Product Search.
If the rate displayed appears to be incorrect you will need to check the Details section for the Security Total Amount and LVR displayed there as this is what the Products section is using.
In the above example, the Security amount is $800,000 so the effective LVR becomes 187.50%. This is why the higher rate is listed at 4.15%
Note, this can also be an issue where no Security Value has been entered and the LVR is listed as 0% as per below.