Blockchain forks have been a controversial subjects since the dawn of bitcoin, there’s two types of forks, one is called a soft fork, this adds more restrictions to the consensus on which the blocks are verified, a block that was deemed valid before the soft fork can be deemed invalid after it, while the other type of fork is called a hard forkm, and it is exactly the opposite, a hard fork loseens the restrictions on which the blocks are verified, so that a block that was deemed invalid before the hard fork can be deemed valid.