Alternative take: Google have deliberately run the platform at a loss using their vast wealth and market postion to destroy all competition and capture the market. Youtube is now the only viable mass-market facing video hosting platform left and has been for a while. Now they have a de-facto monopoly for the type of content they host, they're trying to monetise the audience. Enshittification has begun.

Perhaps worse they have prevented competition as the business model is basically broken - people now don't want or expect to pay for that kind of video on the internet, nor do they want to watch ads. But maybe Google forcing people to watch ads will rebuild the expectation of paying for what you consume on the internet rather than it all being "free" because you are the product.

This isn't a moral issue. Google has full control over who they offer services to.
So they can of course block people using ad-blockers. If my ad blocker manages to get around that and still let me watch the videos, I can of course do that without feeling guilty, too.

They decide what data they serve and to whom, I decide what I load on my pc as long as it's still served.

Youtube is funded by one of the most profitable companies in the world. I understand the desire for Youtube itself to be profitable, but it could just as easily be a loss leader into Google's services and ecosystem.

Video creators on the platform also rely on a share of ad revenue to make a living.

Ad revenue paid to content creators is notoriously low. There's a reason that content creators these days are all sponsored.