That's typical for Amazon, Google, etc. You don't have to pass all of them, just get enough of them (especially the more senior ones, although you might not be able to tell who that is) to like you.
At Google we've capped it so that you'd not see 7 unless there is some need to revise the slate (different job to interview for, or a really badly formed interview) . In fact we found and target 5 nowadays as the statistical change of score for incoming candidates after 5 wasn't dramatic enough to justify the extra trouble.
YMMV/excpetions etc, but still... I remember when we capped it at 8, then 7, now it's largely 5 at most for 95% of the candidates.
I would've given up after 2.
What a broken process.