Declared Net Income in GST But now I want to pay Tax on Gross Income - What to do?

I have a GST with LUT. My primary work is related to the export of services to client in US,

I used to report the income that I received in my bank account in INR and also submitted the INR amount in GST Invoice and also submitted it in GST portal.

However, I realized that the client is deducting some tax in the US and then sending me the remaining payment. Along with this, the client is also reporting the gross income (before the US tax deduction) as TCS under Section 194O. I had never added this gross income in GST filing, and only income I received in bank

Now, I am considering filing my ITR based on the "Gross Amount" before the US tax deduction, but this will lead to a mismatch between my GST returns amount and Gross Income.

What options do I have in this case? Will there be a big penalty considering GST is 0% as it's export of serivce? The difference would be around 8-10L.