I'm having the same problems as Ritli B., I've been observing weird seeming holes in the walls that my players can see through even though light appears to not be passing through.
https://i.imgur.com/R3kWkLk.png
The diagonal lines of rock walls are not meant to be seen.
What I've noticed is that the maps having issues seem to be the maps where I've snapped my vision lines to the grid using shift+click. Lines not made using the snap to grid function seem to work correctly more often than not, but having to redo the lighting on all my maps is going to be pretty irritating...
It also appears whether I have "Dim Light Reveals" enabled or not, and no matter what browser or extensions I have enabled.
What's weirder is that it seems to be just... Random tiles, not necessarily straight lines.
https://i.imgur.com/o57fEnt.png
I've tried both joining as a player and using CTRL+L as a GM, and has the same vision issues; my players can see it too. Nothing interesting in my console, and I've observed it in Chrome, Firefox, and Edge on Windows and Mac alike.