Packer post process amazon-import changes grub configuration

Hi Team ,

I am using packer to build AMI from kickstart file using qemu module and then use amazon-import post processor to import and create AMI in AWS .

Recently we made a change in kickstart which changes the GRUB_TIMEOUT to 5 from 30.
I see qemu output with GRUB_TIMEOUT as 5 .

Image is then imported to AWS using amazon-import post-processor and I see grub GRUB_TIMEOUT is changed to 30 and there is a backup file created as grub_bkp.

[root@i-0f0a6b7ce10bf9cba default]# ls -l /etc/default/grub*
-rw-r–r–. 1 root root 400 Nov 16 2023 /etc/default/grub
-rw-r–r–. 1 root root 399 Nov 16 2023 /etc/default/grub-bkup

Does any one know why this backup file is created and original grub is reverted ?