Enlighter is a free and easy-to-use syntax highlighting tool for WordPress. However, after installing it, I found that it couldn't display the syntax highlighting correctly. Later, I discovered that there is actually a compatibility issue between Enlighter and Autoptimize. Referring to the installation instructions for Enlighter, the first item mentioned this issue.
Based on the above clue, by adding "enligher/resources" to the settings of Autoptimize, the syntax can be correctly highlighted.