git bisect is a really useful tool when you want to answer the question "when did this thing change?" but it's hard to understand from just looking at the git logs.
The way git bisect works is that you define a "good" and a "bad" commit. The git bisect command then uses a binary search to narrow down the commit that made the repository go from "good" to "bad".
You can further make your life easier by asking git bisect to execute a script for you on each commit, automating the search, and providing the commit in question with no further manual intervention.
Below is an example, with an example script, that illustrates how git-bisect was used on the 121-platform to find the answer to the question "when did typeorm start generating nonsense migrations?".