public static class Texture2DExtensions
{
    public static void PreMultiplyAlpha(this Texture2D texture)
    {
        // Check if the texture has an alpha channel
        if (texture.format == TextureFormat.Alpha8 ||
            texture.format == TextureFormat.ARGB4444 ||
            texture.format == TextureFormat.RGBA32 ||
            texture.format == TextureFormat.RGBA4444 ||
            texture.format == TextureFormat.RGBAFloat ||
            texture.format == TextureFormat.RGBAHalf)
        {
            // Get the pixel data of the texture
            Color[] pixels = texture.GetPixels();

            // Pre-multiply the alpha values of the pixels
            for (int i = 0; i < pixels.Length; i++)
            {
                pixels[i] = new Color(
                    pixels[i].r * pixels[i].a,
                    pixels[i].g * pixels[i].a,
                    pixels[i].b * pixels[i].a,
                    pixels[i].a
                );
            }

            // Set the pixel data of the texture
            texture.SetPixels(pixels);
            texture.Apply();
        }
    }
}