If you sell anything online, your product photos are the most-stolen thing you own. Dropshippers lift them by the thousand.
The fix isn't a bigger watermark
A watermark helps a human. It does nothing for the bot scanning a marketplace. What those systems read is the metadata and the structured data on the page.
So I register every product shot. The image ships with my copyright embedded, and each one has a public record with machine-readable rights. When a marketplace's system checks, the answer points to me.
It also makes reporting trivial
When I do find a stolen photo, the registry page is the whole evidence package — owner, fingerprint, timestamp, all on one URL.