Double special vision allows to see through walls [DnD 5e]
In a DnD5e campaign, if a player character has Darkvision and one of Blindsight, Truesight, or Devil's Sight active at the same time, they can see through walls as if their token had once been there (fog of war is taken off, but nothing currently there is visible), to the range of their Darkvision, regardless of the range of the other sight mode.
Additionally, such a token gains "I've been there" rights within sight, without range limit (or at least couple hundred feet), as long as there're no walls on the way.
Example here: https://imgur.com/a/jtazaNh
Two players encountered this bug, both (and me) running on Windows 10, freshly updated version of FGU 4.1.0.
The bug was present on multiple maps, for the player controlling the token and for me, the GM, when I was peeking at Player Vision Preview.