You know how, during a big programming project, you have to keep the devs from going "this codebase has a lot of technical debt, let's rebuild the whole thing using Rust and Kubernetes and Deno and move the hosting to Azure and switch databases and use microservices and..."? Designers are exactly the same way. Just as technical fiddling is fun and interesting, making new designs from scratch is just as fun and intere…
I learned to get the team focus by writing a brief (commonly used for Brand Managers in big companies) to keep focus on the deliverables. That helps to avoid these type of issues.