Can we put BIP for full nodes to check if the block comes from a %50+hashpower producer and if so if there is anything wrong they reject it. Is it possible or is it being done?
Like has been explained full nodes only care about the longest chain with the most work and accept as long as the consensus ain't broken. So a 51% attack can't create extra Bitcoin.
51% attack woundnt really benefit the instigator because it would affect the value of their Bitcoin not to mention the cost.