This is actually a good change. If you want to change the security assumptions of Github repository, ie make them somewhat distributed. Then the SHA-1 based commit hash is a major problem. It only costs about 10k in 2024 to find a collision to a random SHA-1 hash. While this costs essentially makes the attack infeasible for most threat models. It does limit how far you can scale this without an obvious footgun waiting for you.

This is a good change, even though there is a massive technical debt in changing such a widespread system. It is worth the effort. Should generations from now still be using SHA-1 for their Git ops? Sometime you have to do the switch, otherwise you will never progress.

For my usecase basically i needed to know that every Git commit pointed at a cannoical blob. With SHA-1 you could generate two blobs which hash to the same SHA-1 hash, while you can do the format verification which helps i could not do that in my usecase as i did not know the underlying data. To fix this i had to very ugly have two methods of referencing any Git object, a cryptographically secure SHA-256 ID and the Git ID SHA-1.