Seed preprint finds DeepSeek V4 long-context retrieval varies by position

A Seed team preprint reports "phase sensitivity" in DeepSeek V4 and V4.1-Flash, where identical information becomes harder to retrieve depending on its position within compressed KV-cache blocks.

The compression reduces memory and attention costs, but long-context retrieval accuracy varied by up to 40 percentage points across positions.

The authors note that average benchmark scores can hide these recurring weak spots, though the findings concern retrieval specifically rather than all model behavior.