This chart illustrate how DeepLeaks calculates the leak probability. In case you want to modify the values, take a look at the chart.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3432135616&fileuploadsuccess=1
The representation is not mathematically accurate and is only intended to roughly illustrate how the mechanics work

In this chart the following values are set:

The mod starts to calculate the probability from minPressureLeakDepth on (0% probability) and will result in a 100% probability on maxPressureLeakDepth. The leakPipePowerModifier for Pipes (1.5) curves the probability line slightly. Whilst the leakHolePowerModifier for Holes (14) curves it very much and delays the appearance of a hole to nearly maxPressureLeakDepth.

DeepLeaks does only calculate the probability when pressure raises / the boat's depth increases.

Since the mod stores how many times you fixed certain leaks, it will use this value to bend the curves further, resulting in leaks appearing in deeper waters. This calculation is done for each leak individually and has limits (you can't fix a leak 100 times and get a 100x bonus). However, the bonus will be stronger on the first few fixes and will lose its effect with repetitive fixes.

There is also a random value involved so you will not get a leak at a specific depth, instead it is around this line. It is also important to understand a propability of 50% is very high since calculations are done multiple times per second.