I’ve also had buyers caught out by this. It’s not your fault - although clients assume it is!
As sellers we can opt to have our live portfolio either on or off. For most gigs it makes sense to have it on as it showcases our work. However what we can’t do as sellers is decide what is shown in the live portfolio and what isn’t. It’s all or nothing.
When a buyer leaves a review they have an option to opt out of having their work included in a seller’s live portfolio. If they don’t opt out and your live portfolio is on, then their work will automatically appear in your portfolio. But of course some buyer’s then panic… and coming running to you asking for their work to be removed - but you can’t do this without getting customer support involved…