I fixed the arkan issue for my own server using my own knowledge, and it is currently working flawlessly with over 300 players. Those who wish to use it can download it from the link below.  https://mega.nz/file/zNBSBCaK#dYSdmLAddwh6vjcklmiMNtgniotYVgzEGoT_0bg-vIQ

if you want to correct it yourself;

Download the original arkan and find the following code

var _bodyPart = entity?.skeletonProperties?.FindBone(info.HitBone)?.name?.english ?? "";

After finding it, delete that code and paste the following code in its place.

var boneProperty = entity?.skeletonProperties?.FindBone(info.HitBone);
string _bodyPart = string.Empty;

if (boneProperty != null)
{
if (!string.IsNullOrEmpty(boneProperty.boneName))
_bodyPart = boneProperty.boneName;
else if (boneProperty.bone != null && !string.IsNullOrEmpty(boneProperty.bone.name))
_bodyPart = boneProperty.bone.name;
}

if (string.IsNullOrEmpty(_bodyPart))
return;