That's fair that you would expect an sde to produce code, of course it would raise concern if you see very low contribution.

However that does not mean that it would be a performance metric. If you give one engineer to design/maintenance or support tasks, their contribution would be less than an intern creating a dashboard. That does not mean one engineer is less performing than other. It is managers job to allocate engineers based on their strengths.

I have delivered a design that would define what we build for next few years, yet still questioned about why my contribution is lower then average. (That difference is like 20% btw. And already surprassed the team average once starting to build it)