It's not installed by default, users need to install it (sudo apt install libwidevinecdm0). Previously it wasn't available at all though, at least not in an official way.

These are some unofficial ways of getting Widevine on a Pi (no longer needed now): https://gist.github.com/ruario/19a28d98d29d34ec9b184c42e5f8b... https://blog.vpetkov.net/2020/03/30/raspberry-pi-netflix-one...