Thanks for your answers, I understand that it is really unlikely that this will happen but wouldn't there be a way to improve BTC's algorithm to consider a large and fast variation of its hashrate (maybe with an average time of the last 50 blocks or any suitable system), some kind of security system to prepare BTC to fight against any eventuality.
Till now, difficulty adjustment algorithm has worked well and I don't think there is any need to change the difficulty adjustment period.
With decreasing the difficulty adjustment period, we would decrease the accuracy of estimating the total hash power. to get a good average, we need enough samples.