The feature called "bookmarks" was recently completely overhauled by Stack Exchange and it is now called saves:

 * [Bookmarks have evolved into Saves](https://meta.stackexchange.com/q/382019)
 * [Recent feature changes to Stack Exchange](https://meta.stackexchange.com/q/59445#375078) - October 2022

One of the changes is that now you can organize your saves to several lists and give them any names you wish. And you can also add a private note to each of the saved posts.