There's still plenty of good content on Youtube. It's just that, like most other social networks, the content enjoyed by the majority of people is pretty much garbage.
To get good content, rather than popular, you have to search for it. Or have a history of watching good content, so the system can recommend more.
Even so, I still ignore the vast majority of Youtube's suggestions.
Letting people choose their own video sample picture definitely has lead to a huge increase in videos with highly sexualized cover photos. Some topics are more prone to it than others. I've definitely noticed a huge increase in the number of videos with scantily clad women as the cover photo. Sometimes even on videos that have much tamer actual content.
I do agree that there's good content on YouTube, but if I watch any garbage at all, the recommendation engine will only recommend that. I wonder if someone has a script that will reset my YouTube history every day. Might be interesting for the algorithm to have a fresh take on me every day to show me what I'm into that day.
I noticed that I started getting woodworking videos featuring hot women that clearly didn't actually know what they were doing. They were just following someone else's instructions.
Some of the followed those instructions fairly convincingly, but at least 1 was so bad and I instantly saw through the ruse.
To be fair, I've also seen some with pretty women that did know what they were doing.
Then, those videos stopped appearing in my feed. I doubt they aren't being made, but I was surprised the algorithm stopped offering them.
To be fair, I wasn't logged in. But it's pretty soul destroying whenever I see the home page. It's a bunch of people "reacting" to things (meaning that they have their mouths wide open in the thumbnail), or worse ("I bought everything at X store"). Just excruciating. That's before you get to the fact that like 80% of front page stuff is compilation videos (i.e. content stolen from users on other sites).
I recently looked for content like "how to run an ethernet cable in the garden" and everything was what I was expecting to see. Real instructions, no clickbait garbage.
To get good content, rather than popular, you have to search for it. Or have a history of watching good content, so the system can recommend more.
Even so, I still ignore the vast majority of Youtube's suggestions.
But again, there's also plenty of good content.