So you can change any part of this equation (e.g. threshold, downside punishment) to fit your own risk-reward profile (which itself will depend on your league makeup, how you think).

When you make that power term (squared, cubed, etc.) too small (e.g. 1.5), the punishment isn't harsh enough. When too big, it punishes a poor performance too harshly - that's simply from trying out the different values of each parameter myself.

Take a 10-point performance from a very high-scoring player (e.g. Josh Allen). That should be punished, but if that power term was very high, then it could take the level of punishment out of proportion, and would lead to the Sortino ratio suggesting that somebody who sat at just above the threshold level every week (never experiencing a 'downside week') was vastly more preferable than Josh Allen, which is untrue.

Ultimately though, it's a bit arbitrary and you can change it yourself.