I did a workaround by defining a string variable with header like that in the initialize value
| Description | Quantity | Sender Name |
|-----------|-----------|-----------|
Then for each row I appended the following string to the string variable
| Column1 value | Column 2 Value | Column 3 Value |
All values can be replaced with dynamic values from different sources
Make sure that you click enter after each line as red arrows show

At the end I added the string to the approval details

When I ran the flow the output would be like that

Also the approval came with the right table format.

Regards,
Emad