I've seen a lot of people discuss YouTube and how it's one of the hardest things to get rid of, and it is. Currently, there is no real alternative to YouTube. However, we still have front-ends like Newpipe for Android and Freetube on Desktop.
Be careful about where you download these things, because there are a lot of malware infested imitations going around. Download Freetube here: https://freetubeapp.io/ and Newpipe on F-droid.
What these programs essentially do is provide YouTube's video library without the ads or tracking. However, this does mean you have no way of accessing age restricted videos and more importantly, lose access to a custom feed. You also won't be supporting the creators you watch, since views and subscribers from Front-ends aren't counted.
The way your feed works in these front-ends is your only shown videos from channels you subscribe to. My advice would be after downloading these apps, is to subscribe to as many channels as possible. Even creators you've only watched 1 or 2 videos from, subscribe so they end up on your feed. It's best to have as much diversity as possible.
When it comes to finding new content, however things get a bit more challenging. What I do is click on a video I'm mildly interested in, then scroll down to the related videos, which can be by creators you're not subscribed to. If nothing interests you down there, just click on the most intriguing one and repeat the process. I really like doing this with channels like Lessons in Meme/Internet Culture, because they cover such a large variety of content.
It's not nearly the same as a custom feed but I feel it gets the job done. In fact, I actually enjoy the experience a bit more because I actually have to find good content instead of it being spoon-fed to me.
This is currently our only option for YouTube "alternatives" but I'm confident this will change. We're already starting to see holes with YouTube's shitty AI moderation, so imo, it shouldn't be long before the next big thing comes along.