LCMV beamformer visualisation

MNE version: 1.4.2
Operating system: Ubuntu 22.04.3

Dear colleagues,

After applying LCMV beamformer on the mixed source space, I selected only volume sources for plotting, and here is my plot.

My question is, what are the measurement units on the activation axis? And is 1e6 a normal scale for this plot or have I done something wrong?

Thank you so much!