This is not an Internet disruption, this is a coordinated shutdown by US social media networks to suppress protests against the illegal arrest of Pakistan’s president by a paramilitary organization.
Citation? I think you have cause and effect backwards? This post and all the news coverage I can find says that the Pakistani government is the one enforcing these blocks. Including wholly disabling the internet for mobile devices in some regions.
I don't understand how US social media networks could cause wholesale internet shutdowns in Pakistan, or why they'd suddenly be inclined to do so. Seems much simpler for the ruling government to require their local ISPs enforce these blocks.