The low freq of the LS50 Meta radiate in a circle around the speaker. If you put it against the wall, then that radiating pattern is disturbed. My LS50 Meta goes down to 80 Hhz and that is still some low end that should not be near a wall.
If the LS50 wireless is the active speaker, then I think that version has built-in DSP for close wall placement. My passive speaker does not have that built in.
I am doing something today considered a no-no. I have put my LS50 Meta and the Magnepan LRS+ side-by-side. It should be a bad idea but so far, the LRS+ sounds good. I will test the LS50 Meta later, but I have the advantage of moving the 5 lb LRS+ a few feet away when playing the LS50 Meta.
I try to keep everything away from the LS50 Meta. The LRS+ seems to have a more direct radiating pattern since it does not seem to be affect too much by things to the side of it.