StrictMode is designed to show issues with components that will make them unusable with concurrent React. When enabled, it prints warnings about the usage of deprecated React features and modifies the behavior of React in development mode so that any issues with components become more visible. One such behavior change is that several functions and methods (e.g. Class component constructor + render, function component bodies) are invoked twice This explains why the console.log statement was printing twice!
The easy fix is to disable React StrictMode by removing the component wrapper. But this would leave us blind to potential issues in the components we create.
The proper fix is to install the React developer tools browser extension which marks the double invoked console.log in a lighter color.