Someone can copy your last idea. They can’t copy the brain that makes the next one.

Anything finished can be copied, and if the work is good, some of it will be. What produced it cannot be lifted: the taste, the reading, the specific set of things you have paid attention to for years. Copies are a step behind by definition, working from an output while you are already somewhere else. The only real protection is continuing to make the next thing.

If somebody takes your work, name it once if that is worth doing, then put your energy back into what is coming. Keep improving the part nobody can see. Staying ahead does more for you than guarding what is already out.