Discovering that another seller has copied one of your designs — sometimes an exact copy, sometimes a thinly modified version — is understandably frustrating, but handling it through a calm, structured process tends to actually resolve it, where an emotional public confrontation often just escalates things without solving the underlying problem.
The first step is documenting clearly, before doing anything else: screenshots of both listings, dates (yours ideally predating theirs, which is why keeping your own dated source files and original listing dates matters, as covered in our reverse image search piece), and a clear side-by-side comparison if the similarity isn't immediately obvious to a third party who hasn't seen both.
A direct, polite message to the other seller is usually the right first move rather than skipping straight to a formal platform report — it's genuinely possible they sourced the design from a marketplace or template site without realizing it wasn't properly licensed, especially if there's a middle party (a design marketplace they bought from) who may have infringed on your work without the reselling seller's knowledge. A calm, factual first message ("I noticed this design appears very similar to one I originally created and published here [link] on [date] — can you let me know where you sourced it?") often resolves genuinely accidental cases faster than an immediate escalation.
If the direct approach doesn't resolve things, or if the seller is unresponsive or clearly dismissive, most platforms have a formal intellectual property complaint or DMCA-style process specifically for this — Etsy, Amazon, and similar platforms all have documented processes requiring you to assert you're the original rights holder, which is where your documentation (dated originals, source files) becomes directly useful rather than just precautionary.
What's generally not worth doing: public callouts on social media before attempting the direct and formal processes, since this can sometimes escalate into a messier public dispute without actually resolving the underlying issue any faster, and can occasionally expose you to your own legal risk if your public claims turn out to be less clear-cut than they seemed at first glance. The calmer, more procedural path — document, message directly, then escalate formally if needed — is both more effective and lower-risk than it might feel in the heat of discovering the copy.