You don't detect black holes in a single photo.

You either detect them by studying the orbit of a close stellar companion (which seems to orbit a massive, non visibile object) or the effect of the distortion they produce on light passing close to them (an effect called "gravitational lensing").

For those reasons, we can't usually detect small, single black holes, even relatively close to us.

It's just your ordinary clickbait terminology. Few people would click an article titled "very small black hole lies about 375 times farther than our closest neighbor".