That's not YouTube, that's the content creators on there. These sponsorship deals make them a lot more money than what they get from YouTube itself. It's annoying and frustrating, but I totally get that they need to do this if they want to make a living from their channel.

If you don't like this, I suppose you can block the channels that do this and only watch amateur channels that aren't in it for the money. Or they make their money from Patreon or other sources.