Can confirm.
I left AWS Premium Support after 3.5y as a Cloud Support Engineer, as my mental wellbeing was simply just worth more to me.
Sure, you get to learn a huge amount in a very short space of time but even that isnt worth your sanity.
As mentioned, its the same repetitive crap over and over, day after day. Unless you're in the top 10-15% of engineers, you'll inevitably find yourself stressing over achieving your weekly and monthly targets (or "metrics" as its called), week after week, month after month, non stop. It gets to you, man.
If you're battling to make your weekly/monthly goals the only option is to put in extra hours, work 12, 14, 16 hour shifts, work on your off days, respond to customers/monitor your cases outside of your shift hours, and cling to your cases in hopes that you get the case resolve to add it to your monthly goal count.
During my time there I've worked with numerous brilliant engineers across all profiles who simply became fed up with the "normal"/expected way of working and operating in PS, who just packed up and exited the company as their health/mental state/family/work-life balance was simply more important to them.
And as much as it gets denied, PS just simply turned into a call centre setup. Engineers are "encouraged" (/forced) to grab/fight over the incoming calls or web chats (you get measured on this as well), and inbetween calls/chats they're told to take email cases to work. The ultimate function of a CSE/CSA is to resolve a specific number of customer cases per week/month and this is one of the 3 core metrics they're measured on.
Simply put, if you like a high-pressure call centre style job where you're monitored 24/7 and where your salary decreases after the first 2 years, AWS is the place for you.