System Information
Win10
2080ti

Blender Version
Broken: 2.90

Short description of error

When the viewport is set to solid mode, the user can use the "Viewport Shading" dropdown menu to change colour to "Vertex"
This shows the vertex colours while in object mode. However, when entering edit mode, the vertex colours vanish from viewport.

This screenshot shows the same cube, left in object mode and right in edit mode.

Exact steps for others to reproduce the error
Load default scene
Paint vertex colours on the cube
Return to object mode
Switch viewport to Solid, and enable Colour>Vertex

Notice how the default cube shows the vertex colours.
Select the cube and enter mesh edit mode.
Notice how the vertex colours have gone.