csv export adding unwanted decimal end of the numbers

What you see on screen is rounded for visualization purposes but the actual value stored in memory is what you see on the csv file.

Maybe you are not storing the changes and that is why you keep getting the full precision value on the csv file. To help us help you, can you turn this into a proper REPRoducible EXample (reprex) illustrating your issue? It would make it easier to give you a working solution.