They're not encoded, but the code blocks are shuffled. That's why disassembly does look straightforward, but it used to thwart BinDiff at the time.

If I understand correctly, that is just randomness comes from parallel compiling and linking.

If you saying there is a whole step just scrambling blobs, i will be very surprised.

That sounds a lot like US9116712, but I don't think its ever been publicly said that Windows does this.

What made you believe this is the case? any examples/links/etc.?

It was a part of our Windows build process when I was at Microsoft. I only assumed that they would keep doing it, but they might have as well dropped the practice.

I don't see how that can be useful when Microsoft publishes debug symbols for almost everything.