A big part of their algorithm is keeping you on the site longer. It does this by showing you many low quality suggestions (because most people will sift through and consume them) before getting to the higher quality videos. Then, just before you were about to leave, they show something likely to keep you there. After being rewarded with a good video people often stick around hoping that they'll find another similar quality video. It hardly matters if this is a learned behavior or a hand crafted algorithm.
They are not interested in learning what videos you like. They're interested learning what will keep you there longer. If this is a learned behavior then pretty much the only way to train the algorithm is to tune out more often.
This is not a system that favors quality content. It favors ad views. This is an ad network. Even if you pay to hide the ads, you still get treated this way. Even if you pay for it, content creators still get treated like shit if they don't produce ad friendly content. Ads are the boss, not you.
I have, in my subscription list, creators that I watch 100% of their content without exception going back years. If left to YT suggestions I'll see that content weeks after release. You must use the subscription page to see content in a timely manor. This is demonstratively so.
My subscription page grows pretty much because I'm tipped off about good content from sources off YouTube or callouts/collaborations from creators I follow.
I don't know how much longer we'll have the subscription page since it directly subverts the malgorithm. You may need to rely on an external tool soon. Remember, you're not the boss despite "you" being in the branding.
Also, even good creators are resorting to click bait in a "if you can't beat them" bid. Yes, the algorithm is having a negative impact on quality. There's not much you can do to fix it. The best you can hope to do is side step the permanent problem. Look me up next year before you call my pessimism misplaced.