Good point, thanks. The way I modeled the adjustment was by assuming that most usage is captured by Statcounter but there’s movement back and forth to a reservoir that flies under its radar, in bursts, with zero net movement in the long run. So I used a geometric mean of the source data scaled by the square root of their averaged ratio.
Hungarian news sites seem to be posting this same piece of news, which supports its authenticity. The only bias here would be whether the media choose to report this or not (reporting bias). So far most European and American outlets are silent.