The exact nature of the mysterious space object currently remains unclear as "there has been no official confirmation” yet.

As the Soyuz MS-12 spaceflight successfully delivered members of the Expedition 59 crew to the International Space Station, the Daily Express notes that “eagle-eyed” UFO hunting enthusiasts spotted a peculiar and mysterious sight that was captured by ISS cameras mere days before the spacecraft’s launch.
A video shared on YouTube, which appears to be a fragment of an ISS live feed from March 11, shows an enigmatic object flying high above Earth but at the same time below the station’s orbit.

While the person who uploaded the footage wondered aloud whether it was a satellite or a UFO, the newspaper noted that “there has been no official confirmation” yet.Source: sputniknews.com