Help with “Action Needed: Update your shipping prices”

I’m an FBM seller on Amazon.ca and just received the following weird email from Amazon:

We removed the ship options for your seller-fulfilled products with excessive shipping prices. Affected ship options are reflected in the following table”

And the shipping option it’s referring to is only $6.49 which I charge for the books I sell, across all regions in Canada. It was also the default shipping fee for books set by Amazon back when I had an “individual” account.

This email continues to state:

Why is this happening?

You appear to be charging excessive shipping prices for one or more of your seller-fulfilled products in violation of Amazon’s Marketplace Fair Pricing Policy. This policy can be found at https:// sellercentral.amazon.ca/help/hub/reference/G5TUVJKZHUVMN77V. In the case where all ship options violate the policy, your offer has been removed. Further violation of this policy may lead to account deactivation.

Now, I don’t understand how a $6.49 shipping fee for books is excessive, especially since many other sellers are charging even more than me and I also have shipping tables that charge $15 in shipping fee but they’re not marked as an excessive shipping fee.

Please help!