docs VS savepagenow

For Spanish you could read the undergraduate operating-systems textbooks by Francisco Ballesteros. There's one for Plan 9 and one for Unix. At a macro level they're basically the same book. PDF of the Unix one: https://github.com/fjballest/docs/blob/master/uxintro.pdf

The paper

Well, you could try using the Internet Archive's Wayback Machine:

Link to website or name of cookbook (note: export a PDF or MP4 to save the original website or video tutorial in case it disappears, also use archive.is & archive.org/web for older recipes that aren't available anymore, like this one)

If you put the link I put above in the following page you can get to a saved version of it https://archive.org/web/

Not sure if it’ll help with this, but https://archive.org/web/ aka the Wayback Machine is good for looking up old versions of websites.

Yeah, the internet already allows you to view any website on any day in history so I still don’t know why that book exists.

yeah you can, https://archive.org/web > scroll down to 'save page now'

Not really, sorry. The best you could do is pop the URL to your bookmarks into the Wayback Machine and see if your bookmarks page was ever captured. Then you could compare your existing page to anything the Wayback has. However, it’s unlikely they would have captured all your bookmarks, or captured them recently, if they ever did.

Accounts you delete/make private may still be viewable via the Wayback Machine. Search it for any URLs related to your accounts, and if they come up, you can follow the steps here or send a GDPR notice similar to how this person did to have them removed from the archive.

Maybe try the Wayback Machine at Archive.org if you have the playlist URL? https://archive.org/web/ I'm not sure it archives that type of thing but worth a shot. Otherwise I'd say start a new playlist asap while your memory is fresh and try to back up the list in a 2nd location somehow (even if it takes a lot of effort, like typing it all out).