Yeah $400K is high L5. Not uncommon, but slightly above average. It's possible that if you average all engineers you'd get something close to $400K, but L3 and L4 salaries would bring that value down. In surveys L5 makes up the majority of the engineering workforce in these companies, and L3\L4 have a bigger representation than L6+, so it's unlikely that the average TC is $400K.