Julia can type Greek characters with [\alpha + tab], but if I put a comment out with backquotes above the `function`, it doesn't work

Why does [tab] completion not work?

Preparing to type Greek letters in Julia

using LaTeXStrings

it work.

function hoge( xₜ )
   # code ... 
end

it is not working. ( I’m putting in a backslash to prevent it from being rendered. )

\```
markdown ...
\```
function hoge( x\_0 )
   # code ... 
end

In JupyterNoteBook, I could type Greek letters without loading anything, but in JupyterLab, I needed LaTeXStrings.
I wonder why this is so.