Ive been out of tech for a long time but it is odd that there were multiple issues.
Redundancy was king in our data centers. Any important applications or servers that were installed had to also be installed globally. We would have servers go down and the end user never knew a thing.
If i had to guess this could have been a network device like a router or hardwired fiber optics impacting a single data center. Maybe even an issue with one of their telecom carriers
I actually started having some issues with FB a few days ago before the big problems yesterday. Starting about Monday everytime I sent/replied to a private message that a friend sent me, my reply to them would show up in my messenger as a new mesage sent to me. Which was odd. Then I kept getting the same "new posts" notice every time I would click off and back on the site. So seemed like they might have been starting to have some issues even before yesterday. Seems to be normal so far this morning. Truth be told I don't even like FB. If it weren't for my business I probably wouldn't even have a FB account.