In the meantime, since there's a strong recommendation to no use mounts across operating systems (i.e. "/mnt/..."), I create my projects directly in the Linux File System (i.e. "\\wsl$\Ubuntu\home\trogne\myprojectname").
You can read the recommendation here : https://docs.docker.com/docker-for-windows/wsl/
And there's also an alert for that in vscode if you launch it ("code .") in a "/mnt" folder: "This workspace is on the Windows file system (/mnt/). For best performance, we recommend moving the workspace to the Linux file system (~/home)."
I also create a symbolic link :
mklink /D lar8frsc "\\wsl$\Ubuntu\home\trogne\laracasts\lar8frsc" symbolic link created for lar8frsc <<===>> \\wsl$\Ubuntu\home\trogne\laracasts\lar8frsc
Then I can "code ." from within my windows folder.