At some point, it helps to broaden your programming language exposure, even if you stick to mostly one language for most of your work. You'll find ways to apply ideas from other languages/communities to your work.

Try to spend some time learning idiomatic programming from one of the Lisp family (Scheme, Racket, CL, Emacs Lisp, and Clojure all have different thinking, but a lot of overlap). Play a bit with Smalltalk or a similar descendant, even if you're already doing OOP elsewhere. At some point you should learn a textual expansion language, like one of the Unix shell scripting ones, or Tcl (and learning basic Bash scripting will probably be useful in tech work). Try a logic programming language, like Prolog, or one that's a minilanguage within another, like Mini-Kanren. Maybe buckle down for hardcore functional programming (e.g., Haskell, OCaml, or discipline yourself to do it in a Lisp?). You should also get comfortable with C or at least an assembly language at some point, to have a better idea of what other languages are and aren't giving you, and also C is just a really useful thing to know when you need to write a little fast code, FFI to a native library, or get into languages/IRs for newer target architectures.

(Disclosure: I've been especially involved with Racket, an energetic close descendant of Scheme, and have some interest in promoting it, but I'd list a Lisp as one of the first in any case.)