Why is my Laravel Inertia Lambda rendering pages inside nested modals?

Question

I have a Laravel app that works fine locally using Docker/Sail. However when I deploy that app to an AWS Lambda, it doesn't function in the same way. Once running as a Lambda, every time I navigate to a new page, the new page loads in a nested modal. My installation is pretty vanilla. Any idea as to why this would break as a Lambda, but behave differently running locally on Docker?

As I first starting debugging this, I did notice that request header key cases didn't match. For instance, Content-Type when running locally and content-type when running in a Lambda. Some of the middleware seem to check for certain header keys, but they were typed with upper cased words in code.