Of course big and influential media companies favour one side over the other. That's been happening long before the internet. It's called propaganda and has been the practice of traditional newspapers, radio stations and television networks since the beginning of their existence. And that will continue being the practice. Now the questions are: how much does it matter? can/should we try to control it? what are the proposals for that? how to enforce it fairly for every political group? --- note the current government (the one complaining about Meta favouring the opposition) also has its own propaganda network favouring itself against the opposition.