The powershell 6 preview 4 icon is very, er, edgy:

More to the point, it's not Windows icon guidelines

• it's got a lot of detail - Windows icons are generally a few basic shapes
• not all the detail is recognisable - what is the curvy pink line?

This may be a test icon for preview releases (in which case close this bug) but a modern version of the previous icon (removing the gloss etc) would be much better.