Shader old film from MIZIZIZIZ. Conversion of this tutorial: http://fernandourquijo.com/index.php/2017/06/11/analyzing-and-emulating-limbo-style-shader/

old_film

shader_type canvas_item;
render_mode unshaded;
 
uniform float randx;
uniform float randy;
uniform float grain_scale : hint_range(0.0, 1.0);
uniform sampler2D noise_tex;
uniform sampler2D vignette_tex;
 
 
void fragment()
{
    vec4 col = texture(SCREEN_TEXTURE, SCREEN_UV);
    float lum = col.r * 0.299 + col.g * 0.587 + col.b * 0.114;
   
    vec2 offset = vec2(randx,randy);
    vec4 noise = texture(noise_tex, mod(SCREEN_UV * grain_scale + offset, 1.0));
    vec4 v_fade = texture(vignette_tex, SCREEN_UV);
   
    COLOR.rgb = vec3(lum, lum, lum) * noise.rgb * v_fade.rgb;
}