I tried out codespaces online (configured with docker-compose, here is the repo: https://github.com/mmarcon/fun-with-countries). Overall works great, but I noticed that some extensions sometimes are missing some of the icons and other resources (e.g. language definition files)
Some extensions where this problem is visible are MongoDB for VS Code and the Azure Databases extension.
The errors in the browser’s dev console are 502s port not forwarded or something like that. I also noticed that after a while, if I refresh, all the icons and language definitions are there.