Firstly, BreadTube is NOT liberal in any sense of the word, because 1) they are socialists and communists economically; 2) their cultural analyses are also based on Marxian and critical theory type analyses, rather than the liberal values of Locke, Mill or Rawls. New-Leftists loathe the mainstream conflation of ‘left’ and ‘liberal’, but I as a classical liberal loathe it just as much. New-Leftists believe in class or group-based struggle against ‘structural oppression’, liberals believe in individual-level liberty and equality. New-Leftists believe in consciousness being caused by material conditions (hence their lack of concern for free speech), liberals believe in the primacy of ideas (hence our strong support of free speech).
Secondly, I don’t think the right is as dominant on YouTube anymore. I actually think that BreadTube is the largest growth area nowadays. The right’s huge subscriber counts were mostly accumulated in the past, probably mostly before Trump was elected. (This, in turn, probably reflect the ever true observation that commentators in the opposition always have a huge advantage.)