Yes you can prevent it

Not possible. Once gone means gone. You should have implement proper policies before implementing your setup if you know your network can easily be compromised.

Yes you can prevent MAC spoofing, but the problem is the configuration that is set to the MAC, l

That is called ARP or Address Resolution Protocol kind of spoofing. Thankfully there is Sangfor Endpoint Secure, Sangfor Cyber Command and Sangfor NGAF that can prevent it from happening.

Yes you can prevent MAC spoofing but the problem is the configuration that is set to the MAC like whitelisting and others.

You cannot prevent MAC spoofing. The problem you're trying to solve is authentication. And the MAC address is simply not the right way to provide authentication since it can be spoofed very easily. There are even legit reasons to spoof a MAC address.

Have u try to use MAC address authentication?
Only devices with a verified MAC address can access the IAG services associated with a particular username and IP address