Hi am new to strapi, and am kind of finding it hard to make use of the thumbnail images. seeing this post made me happpy, but there is no solution here… 
updated:
Solution if you are using the thumbnail
const ApiUrl = ‘http://localhost:1337’; // or deployed URL if working in a production enviroment
<img src={ApiUrl + data.img[0].formats.thumbnail.url} alt={data.title} />