You are more likely to get locked in with kubernetes than with AWS. It’s easier to migrate out of highly decoupled, well documented systems piece by piece (AWS) than out of monolithic frameworks like k8s.
You can take as much time as you like to migrate yourself away from k8s if you don't like it any more (physically migrate your system to your own site; pin the k8s version to prevent API changes; then start changing your code to be less coupled to k8s.)
Whereas, if AWS changes and deprecates a feature, you're on their schedule as to how long you have before your service will break.
If your application runs on K8s, then it's portable and it doesn't have to be aware of the environment or other system integration (e.g storage).