Can bitcoin history be changed?
Yes, Bitcoin Core can and will change the blk*.dat files, which, as has been told to you many times before, can be different for all nodes. Once Bitcoin Core has validated a block, it updates its chainstate database so that it knows what its current blockchain tip is. It also updates that database with the most recent UTXO set. So once this is done, the block can be thrown away as we have now recorded that we validated it. This is what pruning does; it throws away old blocks that we have already validated. Having the correct chainstate (UTXO set and blockchain tip) is all that matters.