I confirm what @framilano did.
I did this tutorial https://quarkus.io/guides/aws-lambda.
When I actually added the lambda on AWS and created a FunctionURL for it, I started to get null pointers.
Then, I had an idea.
I tested my lambda to receive a JsonNode (jackson.databind).
This revealed that the object which was actually passed to my handleRequest() method was a APIGatewayV2HTTPEvent.
This is the logs on CloudWatch:
After I changed the object on handleRequest(), it worked properly.