Your z-limits are fine, the fact that the mesh is in the 6.8-7.8mm range is normal, and is based off the height of the bed. The issue I am pointing out is that the left side is roughly 1 mm lower than the right. Again, if you don’t want to fix this and you aren’t having issues then that’s fine, but if you want to fix it then I would recommend tramming your x-axis.
This is something that has been discussed on the forums pretty extensively, and I would again implore you to look up “tramming” on the forums. I’ve linked a couple threads below if you’re interested.