the main perk is not that it removes ads but that there will be slightly less of them.

It does remove ads in most videos, just not in Shorts, or on music videos. The whole deal is they’re essentially un-bundling a music subscription from YT Premium, which makes it cheaper, and is then better if you, say, watch YouTube, but already use Spotify for your music.

Essentially, you don’t see any ads when you watch videos, AKA no midrolls, but you might see a small banner ad above the list of next suggested videos to the right of the video player, and if you constantly scroll shorts they might toss some ads in there as well.

Personally, as someone who doesn’t use YouTube for music, and doesn’t like scrolling shorts, I see this as perfectly reasonable as a way to reduce the cost, especially when you can click the Theater mode button on any video to block out the majority of the suggested videos area by default before any sidebar ad would even make it on your screen.