Why when I use the GFX - rs program, there will be a white block

The white space appears in the first few seconds, when I compile an gfx-rs’s example based on OpenGL whatever I choose gnu or msvc on windows10. .
but I tried it on ubuntu, the withe block didn’t display.
When it runs on windows it looks like this:


So is there any way to avoid this, or is it a platform problem?