This is in part where the "It's always Day 1" mentality manifests at Amazon.
There's only one programming language that is forbidden (PHP - for wrong reasons), and only one cloud vendor that is mandated (obvious). But beside that, teams are able to use literally whatever technology they want. There are some technologies that impose themselves because of the ecosystem, but you can always do your own sauce if needed.
I've been in two teams that had basically 90% different tech stacks, but it's never a problem, and it doesn't really ever come up in design reviews (unless there's a real reason, not for personal preferences).
There's only one programming language that is forbidden (PHP - for wrong reasons), and only one cloud vendor that is mandated (obvious). But beside that, teams are able to use literally whatever technology they want. There are some technologies that impose themselves because of the ecosystem, but you can always do your own sauce if needed.
I've been in two teams that had basically 90% different tech stacks, but it's never a problem, and it doesn't really ever come up in design reviews (unless there's a real reason, not for personal preferences).