It does, it means it was created for the use of AWS. That means the primary reason for the patches it is to make sure it will work well on AWS.

While the product is free it doesn't mean the patches will be beneficial anywhere else, in fact if it will work better anywhere it would be merged back to OpenJDK and we wouldn't need the fork.

Same thing with Amazon Linux, sure you can use it on premise, but it is tuned to work best on AWS and might actually work worse outside than other distros.

As someone else pointed out, AWS does consistently upstream things to OpenJDK and is in fact regularly one of the largest contributors.

Additionally, the entire thing, again, is open source and with a permissive license meaning nothing is stopping anyone from forking it and doing what they'd wish with it.

You are in fact right that it was created to work well with AWS, but I fail to see how that is 'lock in', since most of those benefits are probably benefits on any modern cloud - since AWS does not generally run on a particularly unique architecture.