configure is regenerated from configure.ac using a custom container with appropriate version of tools (quay.io/tiran/cpython_autoconf by Christian Heimes). As a result, configure falls into the same category as files generated by Argument Clinic, Freeze and Parser/asdl_c.py. Due to size and churn of these artifacts, they are marked in .gitattributes as generated so GitHub Pull Request Diff Viewer collapses them into a short notification. The pull request associated with this issue does the same for configure.

Actually, configure diff is so large that sometimes it crosses a threshold and GitHub collapses it by force with "Large diffs are not rendered by default" or even "xxx additions, yyy deletions not shown because the diff is too large. Please use a local Git client to view these changes". See GH-29756 as an extreme example (15,430 insertions and deletions) and <https://github.com/python/cpython/commits/main/configure> for an average.