Parallels Desktop Dock and menubar icons along with the shared app icons have been updated to better coexist with the latest macOS versions. We expect the redesign to bring a delightful and cohesive experience for you. As shown in the screenshot below, red vertical Parallels logo bars are no longer visible on the shared app icon.
If you'd like to have a better option for differentiating Windows and macOS Dock icons you can tag a virtual machine with a color in Control Center:
1. Right-click the Parallels Desktop icon in the Dock > Control Center.
2. Right-click the virtual machine name and select a color.
As a result, the virtual machine icon and shared apps icons will look so.