It seems global copyright enforcement with blacklisting and blocklists:
https://github.com/ipfs/notes/issues/284
(I've testified in US federal court in copyright cases as the expert witness professor. I always try to investigate the DMCA decisions of developers. Difficult tradeoffs.)
Note that outside of special cases like a publicly-accessible gateway, an IPFS node is not supposed to fetch or retransmit data that the node operator has not specifically requested to be stored there. So this copyright enforcement stuff will always mostly apply to these services. (There might of course be some corner cases such as fetching a mutable IPNS resource and then rejecting the data because it happens to match some blacklist, but these are also broadly sensible.)
As hobofan said, this is up to each node to update/block. It really seems like that the TOS only goes for their gateway, I don't see how they could enforce this on the entire network.
