Edit 1: What are they actually looking for?
By ten years of experience, you should probably have used all the major tech stacks in your area of expertise. If you're BE, probably Go, Node, Rails, Django, Spring, maybe even PHP. If mobile you should be able to use native, capacitor, PWA, Flutter, React Native, maybe KMP. And so on.
It's sometimes a bonus if you're using something someone has never heard of. Y Combinator is named after a Lisp thing. PG was using Lisp as a hack while everyone else was using C and he credits it for his rapid development speed. Many tools are just built for teams of > 3, and lose the advantage of having a solo dev.
If you're competing with Google's AI team and you use something generic, then... you're probably not going to make it. If you're building something that doesn't require a lot of technical expertise, they might still want to suss out that you know the difference between JavaScript and Java.
That's not real life.
Most Devs get a job and learn a stack and then they stay in that stack unless there is a reason to change
Most BE will know one of either Java or .Net or Python. As that is what most corporates use.
