According to the release notes for the next major release of macOS 10.15 (Mac OS Catalina), from this release, macOS does not include the scripting language runtime by default. In the release notes, Apple said that in order to maintain compatibility with older versions of the software, macOS includes scripting language runtimes such as Python, Ruby, and Perl. However, starting with 10.15, macOS does not include the scripting language runtime by default, users need to install other packages themselves. If some software relies on a scripting language, Apple recommends that developers bundle the runtime in the application.
“Scripting language runtimes such as Python, Ruby, and Perl are included in macOS for compatibility with legacy software. Future versions of macOS won’t include scripting language runtimes by default, and might require you to install additional packages. If your software depends on scripting languages, it’s recommended that you bundle the runtime within the app. (49764202)”
In addition, Apple also advises users not to use Python 2.7, as future versions will remove Python 2.7, which recommends users to use Python 3.