Linux is mostly open source anyway, so all the files are open to inspection to anyone who wants to take a look. This demonstration is showing the ability of windows 11 to run containerised (vm machines) of various OS installs running on top of windows. Looks pretty streamlined, no doubt on a beast of a computer, but this is a fairly natural evolution of a development environment.
I guess your concern (and it’s only a guess) is that your perception of security is around whether linux or windows is the base OS and what is inspecting all traffic/processing on a given instance of whatever platform you “think” you are on. That is a fair question, and the answer is, the user will never know. If you don’t know, you can’t contain the risk, so either avoid situations where the risk is greater than the purported harmful outcome, or use something where you know the risk.
You can liken it to a car. If you have a 1985 Impala, you don’t need to worry about GPS tracking. If you have a modern Toyota, you will never know if you have managed to find all the antennae built into the modern one. You might have to put up with manually winded windows, but if your concern is security, it’s a decent trade-off to not have a satellite staring at you when you go to the store.