"I encourage you to change all your data types to boolean. Whenever there's a data quality issue, it can only be wrong by 1 bit." - Anonymous
Starting out When you're starting out your career as a software developer, you'll typically get a first role as either a backend or frontend dev, and after a couple of years, gain some experience on the other side to become a full stack developer.
Company specific lock in Since every organisation has its own tech stack, a full stack developer in Company A will have a different set of skills than one in Company B. Those additional skills you learn are still useful to boost your knowledge - it can include: specific cloud services, CI/CD, containerization, DevOps processes, a domain specific library or framework, and the company's SDLC process.
At this point many developers stay committed to their company's tech stack and remain working as a full stack developer for several more years. My advice - don't just coast as a full stack developer, branch out!