Masked UI contents of ScrollRect overflow its boundaries with visual artifacts when Deferred Rendering Path is used.

Steps to reproduce:
1) Open the attached project.
2) Build for Linux.
3) Run the build.
4) When the game menu appears, go to Settings > Graphics.
5) Click on "Windowed".
6) Click on "Fullscreen".
- Repeat steps 5 - 6.

Upon switching window mode, the masked UI contents become visible - all the entries of ScrollRect become visible, even though they shouldn't. Switching the window mode again fixes the issue. This also occurs when switching resolution or re-entering the Graphics section.
This issue does not occur if Forward Rendering Path is selected in the GraphicsSettings.

Reproduced on:
5.6.0b3, 5.5.0p3

Tested on:
iMac 21.5" Nvidia GeForce 750M w/ Nouveau display driver