"Mirror image" language from Sputnik is clickbait. Planet and star are generally similar in size to Earth and Sun, that's it.
Since the word "mirror" has a special meaning to this board (think mirror) the word in the article may give anons the impression of there being some kind of deeper substance here, but it really only looks like a clickbait headline.
Another article:
https://www.technologyreview.com/2020/06/05/1002831/kepler-160-koi-456-04-earth-sun-exoplanet-habitable/
Astronomers have found a planet like Earth orbiting a star like the sun
About the size comparison: "From what researchers can tell, KOI 456.04 looks to be less than twice the size of Earth and is apparently orbiting Kepler-160 at about the same distance from Earth to the sun (one complete orbit is 378 days). Perhaps most important, it receives about 93% as much light as Earth gets from the sun."