Seams on noise WGSL shader, but not in gdshader (godot)

[PraxTube]

left is wgsl, right is gdshader

Bevy MRE here

I am trying to port a water shader written in gdshader to WGSL (in Bevy).
However, I noticed that there is some seaming going on. After some time I figured out it's that the blur of the noise isn't transitionless.

This strucks me as extremely weird as it works seamless in godot, but creates these ugly edges in WGSL (Bevy).
The code I use in the .wgsl shader. Also in this MRE repo.

fn rand(uv: vec2<f32>) -> f32 {
    return (fract(sin(dot(uv.xy, vec2(23.53, 44.0))) * 42350.45));
}

fn noise(uv: vec2<f32>) -> f32 {
    let i: vec2<f32> = floor(uv);
    let j: vec2<f32> = fract(uv);
    let blur: vec2<f32> = smoothstep(vec2<f32>(0.0, 0.0), vec2<f32>(1.0, 1.0), j);

    let a: f32 = rand(i);
    let b: f32 = rand(i + vec2<f32>(1.0, 0.0));

    return mix(a, b, blur.x);
}

@fragment
fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
    let UV = in.uv * 10.0;
    return vec4<f32>(vec3<f32>(1.0) * noise(UV), 1.0);
}

The .gdshader is as far as I can tell exactly the same, so I assume it's either WGSL or Bevy that is doing some magic here.
Or I am just incredibly blind.

float rand(vec2 input){
	return fract(sin(dot(input,vec2(23.53,44.0)))*42350.45);
}

float noise(vec2 input){
    vec2 i = floor(input);
    vec2 j = fract(input);
    vec2 blur = smoothstep(0.0, 1.0, j);

    float a = rand(i);
    float b = rand(i + vec2(1.0, 0.0));

    return mix(a, b, blur.x);
}

void fragment(){
    COLOR = vec4(vec3(1.0) * noise(UV * 10.0), 1.0);
}

How can I get rid of the transition issues? I know that using pre backed noise textures
is much better for performance and all, but that is not my concern right now.
I don't understand why the behaviour differs here.

The different in color (brightness) is related to #8937, that should not be the reason we get the seams though.