Impact
When a transaction contains a dep group with many cells, the resources required to process it are not linear to the transaction size nor spent script cycles.
Patches
In 0.43.3, nodes drop the transactions relayed to them when they contain a dep group with more than 64 cells. They do not ban peers who send them such transactions.
In 0.100, the consensus disallow transactions using a dep group with more than 64 cells. Peers relaying such transaction must be banned. Blocks committing such transactions must be rejected.