Why igst payment is attracting cgst and sgst late fee?

Hi,

I export services from india to other countries. I has to pay 18% integrated tax without LUT.

It is stated that there is no late fees on filing IGST. then why GSTR3B is displaying late fees under CGST and SGST when I am late in filing the return in the next month form?

and what is the purpose of the late fees when Government lose nothing since they have to refund the amount as GST is not applicable on it?

thanks