C and C#, possibly Go (one of C# or Go based on jobs).
Learning C via "C Programming: A modern approach" to have a deeper understanding of memory management, stack/heap, lifetimes, pointers, low-level etc
Learning C# for my career, and to get more familiar with SOLID, OOP, Backend coming from TypeScript/Python
In 2025 I plan to try either C++ or Rust for graphics programming