Reproduction steps:
1. Create a new Unity project.
2. Create a new "Cube" game object.
3. Open game view.
4. Move "Zoom" slider to the middle of the bar.
5. Try to move slider, that appears on the bottom of the game view.

Actual result: game view flickers, shrinks and stretches repeatedly(GIF attached).
Expected result: camera moves sideways.

Notes:

• Distorted view resets when game view window is resized.
• Camera preview is not distorted(picture attached).

Reproduced with: 5.4.0b2, 5.4.0b10
Not reproducible with: 5.4.0b1