Again, it is not a "Custom OS" you aren't installing it as an OS from an ISO. You are still required to have your own licensed version of windows and install that prior to using AtlasOS. Using it does not cause security and instability issues as long as you understand what you are doing. Yes it is stripping things from windows. It's also open source so if you were so inclined you could see exactly what is being done.

If you equate using an automated solution to do things that you could do manually albeit with a bit more work involved, then every single OS is custom the second you change anything on it.

I do use Linux for what it's worth and have been for around 20 years. I've also been working in Tech for the last 15 ish years. I wouldn't be blindly recommending something that would wreck someone's security.

Please do some research.

https://github.com/atlas-os/atlas

There's a link to their source code. They even state that you have options to what security settings get messed with. So again, as long as you READ and understand what you are doing, you aren't necessarily breaking your systems security.