pixijs: Mask ignored when rendering on RenderTexture (Firefox Linux)

I’ve added a masked sprite to a container, when I render it on screen the mask works correctly but when I try to render it on a RenderTexture the mask is ignored. Problem is, I tested it in some environments, here’s the list:

	Windows 10	Manjaro KDE
Chrome	Ok	Ok
Firefox	Ok	Bug

I have no clue on the bug’s origin. I’ve created a simple playground, in the upper half you can see the pixi.js behaviour and in the lower half you can see the RenderTexture behaviour.

Expected Behavior

Current Behavior

Possible Solution

I don’t know of any, maybe using filters will bypass the bug but I haven’t checked.

Steps to Reproduce

Get linux + Firefox (I think?) and use this link below. https://www.pixiplayground.com/#/edit/iJ6CBxiP5PGlzGXt7zi1s

Environment

• pixi.js version: 5.3.3
• Browser & Version: Firefox 79.0
• OS & Version: 5.4.57-1-MANJARO + KDE Plasma 5.12.4
• Running Example: https://www.pixiplayground.com/#/edit/iJ6CBxiP5PGlzGXt7zi1s