My background in architecture gives me a useful way to think about this question. Understanding how a structure works informs the design, even when a specialist is responsible for the detailed engineering. Digital interfaces also have a medium with constraints that are worth understanding.
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The analogy has limits. Software changes continuously, and design and engineering responsibilities can overlap substantially. Still, it helps distinguish learning enough to make better decisions from assuming every designer must become a production developer.
Start with a recurring problem
For web product work, understanding layout behavior, semantic elements, component states and asynchronous updates can improve a design discussion. A fixed-width mockup may look fine until a translated label wraps or a request leaves the interface waiting.
For Game UI, focus navigation and changing game state may be more immediately relevant. The useful learning target depends on the work. A broad coding course is not automatically the best next step if it avoids the interaction you actually need to understand.
Build a small example and expose the failure
Try implementing a form with an error and a loading state, or a menu that can be operated without a pointer. Change the content and interrupt the expected sequence. The exercise becomes useful when it reveals a behavior that the original design did not specify.
Bring those questions back to a developer. An experimental implementation can make a discussion concrete, but it does not establish that the approach is secure, maintainable or appropriate for the product's architecture. Knowing a little code should make you more precise about those limits.
Consider what you are postponing
Time spent learning implementation has an opportunity cost. If the biggest weakness in your work is understanding users, a more sophisticated prototype may not help. If your concepts repeatedly break during implementation, technical practice may address a real gap.
A designer who can inspect behavior, communicate constraints and revise a proposal has gained something valuable even without writing production code. A designer who chooses to specialize more deeply in implementation can go further. The decision should follow the role and the problems you want to solve, rather than a universal rule about what every designer ought to be.