Game filters: wrong size?

Code snippet reproducing the issue:
PlayState.hx

package;

import flixel.text.FlxText;
import flixel.system.FlxAssets.FlxShader;
import openfl.filters.ShaderFilter;
import flixel.FlxG;
import flixel.FlxState;

class PlayState extends FlxState
{
	override public function create():Void
	{
		super.create();
		FlxG.game.setFilters([new ShaderFilter(new BorderShader())]);
		FlxG.game.filtersEnabled = true;

		var text = new FlxText();
		text.text = "Hello World!";
		text.screenCenter();
		add(text);
	}

	override public function update(elapsed:Float):Void
	{
		super.update(elapsed);
		if (FlxG.mouse.pressed) FlxG.camera.shake(0.01, 0.1);
		if (FlxG.keys.anyJustPressed([ONE])) FlxG.game.filtersEnabled = !FlxG.game.filtersEnabled;
	}
}



class BorderShader extends FlxShader 
{
	
	@:glFragmentSource("
        #pragma header
		
		void main()
		{
			vec2 uv = openfl_TextureCoordv;
			vec3 col = texture2D(bitmap, vec2(uv)).rgb;
			
			if ((uv.x > 0.0 && uv.x < 0.2) || (uv.x < 1.0 && uv.x > 0.8) || (uv.y > 0.0 && uv.y < 0.2) || (uv.y < 1.0 && uv.y > 0.8)) {
				gl_FragColor = vec4(1., 0., 0., 1.);
				return;
			}
			gl_FragColor = vec4(col, 1.);
		}
	")
	
	public function new() 
	{
        super();
	}
}

Observed behavior:
Game filters appear to detect wrong game size.

This is filter applied to whole game

This is filter applied to whole game after a camera shake

This is filter applied to camera

Expected behavior:
Game filter to look like camera filter

In last image bottom border != top border because screenshot cut lowest part to keep window toolbar (dunno why).

Start with the PlayState.hx reproduction and compare the whole-game filter with the camera filter shown in the issue, including after a camera shake. The work is done when the game filter uses the correct game size and visually matches the camera filter behavior.