It’s those mixing steps that accomplish the one-way nature of SHA-256. What’s claimed here is that if made a version of SHA-256 that only used 31 mixing steps, we could perform collision attacks.

In SHA-256, a binary obtained by evolving the square root of the prime numbers 2, 3, 5, 7, 11, 13, ... Click the red play button in the upper right to go one calculation step.

With Git 2.29, Git can operate in full SHA-1 or full SHA-256 mode, but this means there is currently no interoperability between repositories using the different object formats, SHA-1 or SHA-256.