What Is the Maximum Percentage Change in Difficulty Allowed per Adjustment?

Bitcoin's protocol does not impose a fixed maximum percentage change on the difficulty adjustment. The change is calculated purely based on the time taken to mine the 2,016 blocks.

If the total hash rate doubles in that period, the difficulty will also roughly double. However, in practice, due to the high capital cost of ASICs, the change is usually less extreme, though large swings have occurred historically.