bash script integer comparison syntax error

Question

Following is the bash logic to compile and install Linux kernel if there is an update in the patch number in the Linux kernel version.

post_kernel_postinst() {
    # Extract the new and current kernal verisons
    NEW_KV=$(eselect kernel show | tail -n 1 | grep -oE '[0-9\.]{5,7}')
    CURRENT_KV=$(uname -r | grep -oE '[0-9\.]{5,7}')
  
    # Split the version strings into arrays
    IFS='.' read -r -a NEW_KV_ARR <<< "$NEW_KV"
    IFS='.' read -r -a CURRENT_KV_ARR <<< "$CURRENT_KV"

    # Access the patch version
    NEW_KERNEL_PATCH_VERSION="${NEW_KV_ARR[2]}"
    CURRENT_KERNEL_PATCH_VERSION="${CURRENT_KV_ARR[2]}"

    echo "NEW_KV $NEW_KV"
    echo "CURRENT_KV $CURRENT_KV"
    echo "NEW_KERNEL_PATCH_VERSION $NEW_KERNEL_PATCH_VERSION"
    echo "CURRENT_KERNEL_PATCH_VERSION $CURRENT_KERNEL_PATCH_VERSION"

    # Check if new kernel version is higher than the current kernel version
    if [[ $((NEW_KERNEL_PATCH_VERSION - CURRENT_KERNEL_PATCH_VERSION)) -ge 0 ]]; then
      echo "GoodBye!!"
    fi
}

The above bash script has been working for more than 2 years without any issues, but for the past 2 months or so, it's throwing a syntax error as below,

NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
bash: 3: syntax error: invalid arithmetic operator (error token is "")

I haven't made any changes to the script for more than 2 years now.
Unable to figure out what change in my system is causing this.