How texture func retrieve texel when topo equals point and coordinate is on the edge for example(0.25, 1.0)?

Vulkan
1

glsl

#version 450
layout(location = 1) in vec2 texcoord;
layout(location = 0) out vec4 out_color;
layout(binding = 0) uniform sampler2D texSampler;
void main(){
out_color = texture(texSampler, TexCoord);

magfilter:nearest
minfilter:nearest
mipmapmode:nearest
u:repeat
v:repeat
w:repeat

The image data is four pixel.

enter image description here

The coordinate is (0.25, 1).
I get the red color.
enter image description here
The distance of red and blue pixel to (0.25, 1.0) is equal.
So what is the algorithm of choosing texel when topo equals point?