How to insert the programming language for a code block?

In a rich text field, when I insert

Only the code block is show, and the programming language is not preselected, it is always showing as Plain Text code block.

I’ve no experience in adding the language in via a short code but you can click on the words “Plain Text” in your screenshot. This is also a dropdown that lets you change the language!

Yes, but I like to prepopulate an empty JS codeblock in a rich text field using an automation.
Either with the ‘Overwite Description’ action or using a script.