I faced this same issue in the M1 Macbook pro and fixed it by doing the following

Open ~/.zshrc file (Create a new one if not present already) Add the following line

alias python3="/usr/bin/python3"

Make sure you are able to access python3 from the above location by running

/usr/bin/python3

This should invoke Python3 for you or check for the correct path in /usr/bin and update the above line accordingly. You can do the same for other versions of Python also accordingly.

First, zsh (and as such all other shells) isn't killing python, it's only reporting that is has been killed.

The message 'killed' is a definitive info that the child process (python3 here) has received the uncatchable SIGKILL (9) signal. Unless there's user code that sends itself that signal, it would need a bit of debugging to determine the cause. You could use strace python3 ... to get an idea of what the program was doing at the time. Sometimes, the kernel kills a process, it would report that in the kernel messages available with dmesg.

Sometime in the past you installed a third-party Python interpreter (probably from python.org) which is now obsolete and doesn't work. You need to update it if you want to keep using it. There is also a Python interpreter in Xcode, if you have it installed.

To remove the non-functional interpreter, delete the symbolic link at /usr/local/bin/python3 and also delete /Library/Frameworks/Python.framework. These are not part of either Sequoia or Xcode.

The system Python binary in /usr/bin is merely a stub that invokes the Xcode Python binary, if present, or else prompts the user to install Xcode. The directory /usr/bin is on the read-only System volume and can't be changed by anything except the macOS Installer. Xcode installs only on the Data volume.

Out Of Memory, probably.

You can use a system tracing tool, such as dtrace, to observe the kill syscall being invoked in the kernel, which is how POSIX signals are sent. You are primarily interested in SIGKILL, which is signal number 9.

Here is a dtrace script that will monitor all signals sent from any process to any other process on your system. To use it:

1. Save this script as a file with a .d extension.
2. Give the script execute privileges (chmod u+x SCRIPTNAME.d).
3. Run the script as a superuser (sudo ./SCRIPTNAME.d).
4. Start your Python program.
5. Find the PID of your Python program (e.g., via ps or top) and make note of it.
6. When you see that your Python program has been killed, find its PID in the signal log, confirming that you see signal number 9, and you'll find the name and PID of the process that sent it.

#!/usr/sbin/dtrace -qs

syscall::kill:entry
{
    self->target = arg0;
    self->signal = arg1;
}

syscall::kill:return /self->signal != 0 && self->target > 0/
{
    printf("%s (%d) --> % 6d:  signal %d\n", execname, pid, self->target, self->signal);

    self->target = 0;
    self->signal = 0;
}

dtrace:::BEGIN
{
    printf("SOURCE (PID) --> TARGET:  SIGNAL\n");
    printf("================================\n");
}