Upon launching the notebook, there is syntax highlighting (I am guessing default syntax highlighting for Python). As soon as it connects to the Julia kernel, there is no syntax highlighting at all. Running on WSL 2.
Did you get it sorted out? What is the extension to add the new Jupyter to VS Code?
For now you need to install the Insiders version of VSCode (Download Visual Studio Code Insiders) to get the latest version of the Jupyter extension, which has syntax highlighting and a bunch of other improvements as well (including notebook Git diffs 
)
I am not sure that is necessary. That will enable you to use the fancy “Native Notebook” interface, but it is independent of the other stuff - I believe. In fact, they told me that even though the instructions here say to use Insiders, GitHub - microsoft/vscode-jupyter: VS Code Jupyter extension, it may be a bad idea since the notebooks are sometimes buggy.
At this point, you can manually get syntax highlighting in notebooks with Add configuration files for code highlighting · Issue #1620 · julia-vscode/julia-vscode · GitHub (or at least you used to). More generally, Microsoft is ready to add Julia support directly into the vscode, but it will take some help from the julia community to have a PR. See Julia extension in the core VS Code product · Issue #105229 · microsoft/vscode · GitHub to track
Thanks, good to know there is a solution on the way.