Windows Defender now flags WinAero Tweaker (WAT) as a PUP and removes the executable from the folder.
WAT does not do anything by itself, the user must manually make it do anything.
Every single thing it can do is explained in great detail and can be done by anyone without using WAT.
The only thing WAT does is make it easier, and safer as you avoid mistakes, to both make and undue these changes.
One of the most popular tweaks is the one that disables "Ads and Unwated Apps".
I'm sure this is why M$ has decided to purposley create a false positive in it's A/V software.
M$ is lying to us, plain and simple, winareotweaker.exe is not a virus or a pup.