I also have multiple friends that work at Google, and can confirm that their numbers fall squarely into the bands described on levels.fyi. (In fact, they're often taking home considerably more, due to the aforementioned stock growth and stacked refreshers.)
Several possibilities:
1) your spouse is not in the engineering management track and isn't familiar with the payscale
2) your spouse works in an office with a lower payscale due to regional considerations (though this wouldn't make the numbers look realistic even in "LCOL" US offices, so it'd need to be international)
3) there's some misunderstanding about levels or something else. That Principal Engineers (L8 - three levels above Senior) make 900k-1M out of the gate isn't really disputed; they tend to make a bit more at Facebook, even.
Source: spouse is management level at G of FAANG. Those numbers don't match up with reality in general. For a few edge cases, sure. Not for most people.