Just my experience, but slow start times, high memory usage, tracking down GC pauses, getting the memory flags in line with the k8s resources config, and fat image sizes. All things I enjoy living without.

Also regarding Quarkus, that's java stuff. I don't use it, but I know people do use it for shortcomings of Java in k8s. Perhaps GraalVM is the thing that makes it worth-while, idk.

There's also a distroless Java container from Google that could be of value.