[2019.1.3f1] Blue square on texture first load

When I launch game in playmode first time for editor-instance ( or in build ) some textures appear for a moment as blue squares.

My question is:
- Is this how https://docs.unity3d.com/Manual//TextureStreaming.html works?
- or mb it's some sort of bug?


P.S.: Later I'll attach example-screenshots.