Looks like it's incorrectly including the full 4 year equity grant in the yearly compensation grant.
The hovertext also says they explicitly divide by N.
That said, the person getting such a large stock grant with a lower base salary is suspicious. The other two offers for L6 are clearly correct as they are (160K/year stock is too low for L6), but that one is odd. Doesn't mean it's wrong though.
For some context, initial grants are usually larger than refresh grants, and an L6 SWE (who again is in a lower band than L6 RS) can expect a >200K stock refresh. So a new hire RS at that level isn't going to get less than 200K annually (or 800K/4yr).
Seems well aware that equity offers usually vest over 4 years e.g.: https://twitter.com/deviparikh/status/1310654018654367744