The macOS Monterey 12.3 beta release notes say that the Python 2.7 binary (located in /usr/bin/python) will be removed. Since you follow this blog, this should not come as a surprise. We have been warned about this since Catalina. (Or longer)
That said, the removal of Python 2 in a minor macOS release is surprising. Minor updates should not have breaking changes or removals. Admins and developers may not expect removals and other breaking changes in a minor update and therefore not be paying as much attention to changes. Also, the time a minor update is in beta is usually 6-8 weeks, which leaves us and developers much less time to find and fix problems than a major update beta phase, which is usually 4-5 months.
Nevertheless, we have to work with what Apple deals to us. MacAdmins have been investigating their own tools and scripts since the Monterey release or earlier to avoid the prompts. But when you get vendor pkgs, these might contain anything. While you can inspect pkgs with tools like pkgutil, Pacifist or Suspicious Package, it can get tedious with many packages.
A while back I built a script called pkgcheck to automate this check. Since I (and many others) have started using it again in the recent days, I have added a few more checks to it.
The earlier version would flag files in the installer’s resources that had a /bin/bash, /usr/bin/python, /usr/bin/ruby, or /usr/bin/perl shebang. (the first line with the #!) I have now also added check for a shebang with /usr/bin/env [python|ruby|perl] because when run from an installer pkg, this will also resolve tousing the built-in, deprecated runtimes. Also, using python in the shebang will now be shown as a red error, rather than a yellow warning.
The script will now also grep for use of python in installation scripts and show those scripts. This might generate a few false positives. You will have to use your judgement. For example using python3 in an installation script will also trigger this. But then, it probably should, since python3 is not installed on macOS by default. (What you see in /usr/bin/python3 is a shim that prompts you to install the Command Line Developer Tools, unless they or Xcode are already installed.)
I hope this is useful!