Sorry, no, even in the right-wing Overton window hellhole that is the US, not giving credence to the completely, obviously baseless and brazenly fascist lie that the 2020 election was stolen isn’t bias toward the “center-left”.
The offense I take is that MBFC consistently conflates reporting actual, undeniably factual statements with left-wing bias, which is emblematic of the ridiculous place it chooses to plant its center (US politics is their stated location). But more importantly, even from that ridiculously skewed starting point, it’s patently ridiculous to call these organizations “center-left”.
MBFC is a trash organization that poisons the well for sources by calling them left-biased on the basis that they report true things. They themselves show consistent bias toward the right-wing (for example, they consider both The Guardian and Breitbart “MIXED” in their factual accuracy based on wild double standards) but then try to equate basic factual reporting as political bias.