Extract styles from your app Extract styles from node modules Atomic style sheet Style sheet minification
Check out the docs here https://compiledcssinjs.com/docs/css-extraction-webpack
For a thread on the cool stuff this enables have a look at this twitter thread https://twitter.com/compiledcss/status/1373125637762772996
You can later feel that as a user: bugs, poor performance, accessibility issues. As a developer using this library you can't count on good support.
Atlassian should stick to industry standard implementations, for example styled components.