Hi,
Starting from the new API (4.14) , if I add a Vector Tile Layer to my map and set the visibility to False, and the Opacity to whatever value over 0, then the background colour of the whole canvas switches to a random colour (grey, blue, etc)., instead of white like it was with the previous versions.
https://codepen.io/mtrsklnkvMM/pen/NWPaWXY (example taken from the API Samples)
If you change the opacity to 0 or the api version to 4.13, then it's white again.
It's doing that on the all the computers I tried it on.