After i compiled my kernel, I extracted Image.gz and ran binwalk on this file, and got this output:

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
0             0x0             Linux kernel ARM64 image, ...
283968        0x45540         SHA256 hash constants, little endian

But why at byte 0 the type of content is Linux kernel ARM64 image, and in the stock ROM is undefined (i think its undefined because of some magic number type unknown to Binwalk)

Stock rom kernel:

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
203328        0x31A40         SHA256 hash constants, little endian

That said, did I compile it wrong or something? because my version does not have the same type as the stock rom

The command i used to build the kernel was:

export PATH=/root/.local/bin:/root/bin:/usr/share/Modules/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
export PATH=/android/android-ndk-r26d/toolchains/llvm/prebuilt/linux-x86_64/bin:$PATH

make O=out 
    LLVM=1 
    LLVM_IAS=1 
    ARCH=arm64 
    CC=aarch64-linux-android34-clang 
    CXX=aarch64-linux-android34-clang++ 
    CLANG_TRIPLE=aarch64-linux-gnu- 
    CROSS_COMPILE=aarch64-linux-android34- a34x_defconfig

make O=out -j$(nproc --all)
    ARCH=arm64 
    CC=aarch64-linux-android34-clang 
    CXX=aarch64-linux-android34-clang++ 
    LLVM=1 
    LLVM_IAS=1 
    CLANG_TRIPLE=aarch64-linux-gnu- 
    CROSS_COMPILE=aarch64-linux-android34-

And the kernel is:

https://android.googlesource.com/kernel/common.git