BillboardGuis have strange interaction with ScreenGui parent

[Polymorphic]

ISSUE
If a ScreenGui in a PlayerGui contains a BillboardGui within it with an adornee set, it will also appear on screen as well as attached to the object in world (ie, appearing twice). This did not occur previously.

EXCEPTION
This behaviour does not happen if I parent the BillboardGui directly into the PlayerGui or into workspace.

EXPECTATION
The expected behaviour is that the BillboardGui not appear on-screen, and only in the world attached to the adornee.

GIF OF PROBLEM
https://gfycat.com/DesertedGlassBonobo
A → BillboardGui with text label in ScreenGui
B → BillboardGui with text label in PlayerGui

Notice the top left corner of the screen.

[UnderMyWheel (Wheely)]

This issue has already been reported to Roblox and engineers have logged the bug into their systems.

BillboardGui under a ScreenGui renders in 2D as well

Describe the bug. Describe what is happening when the bug occurs. Describe what you would normally expect to occur. A few days ago I started getting reports of some billboard guis in my game looking massive. It has never happened before and I didn’t change anything that would cause this. How often does the bug happen (Everytime/sometimes/rarely)? What are the steps that reproduce the bug? Please list them in very high detail. Provide simple example places that exhibit the bug and provide d…

[Polymorphic]

Yikes, that post did not describe the issue well enough for me to realize it was related.

In other news, this is a simple repro for the issue. Windows 10 and studio is up-to-date.
billboardguirepro.rbxl (15.3 KB)