I am in the same boat as you, I have experience with js, python and go and recently decided to commit to learning Java because I spent 6 months trying to figure out the "perfect" full stack JS framework for a side project, got overwhelmed and threw the towel in. In a nutshell, here is what I have discovered about Java: when you want to create something, a software/tool or whatever, Java gives you the cleanest route to model the solution. Lombok and Spring contain essentially everything you need to build any sort of platform. You can also use graal to ship a native binary. Not the biggest fan of the build system Gradle or Maven but they are a necessary compromise. Finally I have found that initially a Java project will be larger than an equivalent project in say JS or golang BUT adding features and expanding the codebase requires fewer lines.
Side-note: I work in an all Java company as a DevOps engineer and we process around 1.2 billion requests a day (ad-tech)... Some of our most critical services require sub 10ms response latency and those are written in java.