On Catalina 10.15.7, Apple still included Python 2.7.16 and the idle utility. Both should be in the /usr/bin directory location and these should not be user removable. Since idle uses Tk/Tcl for its GUI, it continues to use the Tk/Tcl 8.5.9 that Apple has shipped for over a decade and it is deprecated. When you launch idle, it will provide this warning on the command line and again in the idle application in blue text. Just press return inside idle to get to the idle prompt.
I prefer to launch idle in the background to free up the Terminal:
idle &
and when done with it, I type ^d within the app.
You really should consider migration of your Python2 code to Python 3.12.1 which is available to you as an proper install package from Python.org, ships with a current Tk/Tcl 8.6.12, and places its python3, idle3, etc binaries in /usr/local/bin.
Apple has removed the Python distribution from the operating system beginning in Monterey 12.3.