In previous versions of the game before 1.18.0, you were able to connect walls and barriers/structure voids together. If this was intentional then all the barriers and structure voids before 1.18.0 that were connected to walls are still connected. I would prefer that both blocks (barrier & structure void) connect to walls. as I personally use it to construct my builds.

The picture, I provided, shows that on the left, walls connecting to structure voids. (before 1.18.0) and on the right it's not connecting (1.18.0 present)