https://larrysanger.org/2020/05/wikipedia-is-badly-biased/
This is the original Larry Sanger article linked in the Breitbart article you linked, and it's a litany of complaints about Wikipedia's treatment of certain pet right-wing causes: Barack Obama's presidency, global warming, abortion, etc.
No: Barack Obama's "scandals" weren't equivalent to Donald Trump's. They did not result in impeachment and to this day have not generated any indictments, despite all the sound and fury over Obamagate which is a ninth-inning exercise in revisionist history months before an upcoming election and should be dismissed as the electioneering it is. More on that later.
Bias is a complex topic, but I side with the current Wikipedia editors who reject the notion that Wikipedia ought to be a platform for "false-balance." Reality does indeed have a "bias" (I won't say a "liberal bias"), and it is one that is often at odds with fringe news sources.
Larry Sanger complains about right-wing topics, but someone criticizing Wikipedia from a far-Left perspective could complain equally about Wikipedia's treatment of other subjects like, say, articles on Stalin or Xi Jinping's leadership of China.
Any article about a current or recent or even long-gone politician is bound to be controversial to somebody somewhere in the world, I reckon.
The best solution to bias that I know of is to read widely and take everything with a grain of salt. The chart I linked above is the best of its kind I have found anywhere on the internet.
I stick to the circled center cluster of sources, typically. I read sources as far left as MSNBC and as far right as Fox News, but I typically stray no further into the fringes on either the right or left because you are likely to encounter unhinged nonsense that is not worth your time.
No source is perfect, but certain sources have a much stronger commitment to reality than others, and Wikipedia is one of them.