Scope creep rarely announces itself. It arrives as “could you just” in an email, a quick sketch requested at the end of a meeting, or a new idea from the client’s sister-in-law. Each request is small and reasonable. Together, they can take a stage well over its fee.
The answer isn’t to refuse change. Clients are entitled to change their minds, and design develops. The answer is to recognise change when it happens and agree it properly before you do the work.