My new warden has come across skill books so they haven't been removed. Are you maybe higher level where you have found a lot of them already?

As a side note..........I wouldn't kiss the patch notes......you don't know who has been touching them!

On PC, rolled a fresh character three days ago, and books are working as intended for me (notifications and increase in ranks, even hidden lines), although I must say I dislike the new way skill lines are handled.

There are more than 3300 Books in the Game, and only 83 of them are Skill Books. You can see if you have read all the skill books in your Journal in the Book section. Find the skill book line and it will show you the count. If your over 60 you rarely find the books as there are so few left and you only find skill books in the shelves, not placed in the world. Well, there are 2 or 3 placed skill books still, but I think they are also on the shelves.

I think the distribution may have changed, but it used to be you would get a new random selection of skill books with each zone you unlocked. So, hit the Mages Guild in each zone and activate every bookshelf. Also, those book shelves in some of the Ayelid Ruins are a good source too.

I have found plenty of skill books on the new Warden, in fact I have unlocked all the skill lines on him through books.

But it is not the only way to unlock a skill line. Just kill something with that weapon equipped, wear 3 pieces of that weight armor, or activate one of those crafting stations. Then you will unlock the skill lines. Note the kill thing, it can be any of those Level 1 environmental critters running around, does not have to be a full fledged mob.