I don't think it's been convincingly argued that ranking or recommendation algorithms necessarily represent any sort of editorial bias. The purpose of these algorithms is to rank content based either on a prediction of what the individual user would want to see based on their existing history or on which content is more broadly engaging in general. In other words, if YouTube decides I really like to watch Ben Shapiro owning the libs with FACTS and LOGIC, that doesn't mean YouTube is making an editorial decision to promote that content, it just means YouTube has profiled me as some sort of conservative. If YouTube profiled me differently, they would be equally happy to recommend TYT videos or whatever.
There may be some editorial bias introduced if the userbase of a given social media site is themselves skewed in a particular direction. For instance, there seems to be some skew in the content that shows up on my Tumblr dashboard that seems fairly irrespective of anything I've subscribed to. But even that isn't necessarily damning for Tumblr, because they're not necessarily making an editorial decision to promote that content.
There may be some editorial bias introduced if the userbase of a given social media site is themselves skewed in a particular direction. For instance, there seems to be some skew in the content that shows up on my Tumblr dashboard that seems fairly irrespective of anything I've subscribed to. But even that isn't necessarily damning for Tumblr, because they're not necessarily making an editorial decision to promote that content.