I used to have similar problems, had to go and clean up julia processes every now and then which all seemed related to vscode.
I assumed it was processes I killed through the vscode interface because they were just hanging, and then they didn’t get actually killed but just detached from vscode somehow. But I never really investigated it, and I haven’t noticed it recently so haven’t thought about it in a while.
So it could be related to the fact that when I killed a GLMakie window that was not responding, the julia process seemed to die (terminal dissapeared, window closed), but in fact the julia process survived somehow…
On Windows here, VS Code process management is also a problem.
For example (unrelated to Julia), the Latex Workshop extension regularly leaves pdflatex processes and perl processes hanging around after closing VS Code. Since I spend my life opening repositories with latex documents, I end up having to manually kill them once in a while (the other day I had 7 perl.exe running for nothing…).