Any sane bgp neighbor has prefix limit ACLs and prefix filters in place on their edge connections to another peer. As an ISP that announces a lot of space and customer space to 2 upstream transits, every time we take on a new downstream customer that brings their own /24 or bigger, we need to have our upstream transit providers update their prefix-list filters.
If our upstreams were clueless or negligent, it would be possible to get into a situation such as when a Pakistani telecom announced a huge chunk of V4 space that is YouTube, effectively DDoSing their international submarine links and also taking down YouTube for some users worldwide.
If our upstreams were clueless or negligent, it would be possible to get into a situation such as when a Pakistani telecom announced a huge chunk of V4 space that is YouTube, effectively DDoSing their international submarine links and also taking down YouTube for some users worldwide.