Fog of war is "open" if you reconnect

Whenever i reconnect (there are a lot of reasons why), fog of war, in map too, is bugged out in a very confusing way, i am forgetting to record that bug, because of the intense moments in the game, but people who've seen it will understand me. Basically on map and screen, in several places where there's no vision, it's shown "open" while it is not. It's very confusing... for example if that is happening on a lane you can witness minions or champs come out of nowhere, because you don't see the range of fog of war.