The problem there is that the terms are often ambiguous, and thus an explanation of how the terms were violated will be ambiguous. "Some sort of legislation ... to force companies to explain decisions ..." will be useless unless the terms are unambiguous. Look for example at youtube where there is a lot of subjective wiggle room in their definition of acceptable content.

Let's face it, the decisions of Paypal and others (Youtube, Twitter, etc) when deciding who stays and who goes on its platform are ideologically and politically motivated. The leaders of these companies are basing their decisions on their own political leanings. And in the vast majority of cases like the Daily Sceptic where a user or service is being deplatformed, the reason is idealogical (rather than a case where the user is for example defrauding the platform or service provider).

I believe a better solution would be for the government to penalize companies that are repressive to the rights granted to us in the bill of rights (for example free speech). This whole "but it is a private company who gets to dictate what speech they want and don't want on their site" needs to go out the window. If a company wants to operate within the US, it needs to respect the rights of the country's population (rather than define its own set of rights).