Incident database / 2025-04-08

Llama 4 Maverick LM Arena submission used unreleased experimental variant

Benchmark presentation (not an attack)Llama 4 Maverick

Meta's leaderboard submission was an experimental chat-tuned variant, not the released weights, inflating public perception of the released model. Recorded under transparency: disclosure practices are part of the risk surface buyers rely on.

Outcome. LM Arena updated its policies; Meta acknowledged the variant difference.

Sources

Sources (1)

LMSYS statement
LMArena leaderboard statements · independent eval · source tier C · lmarena.ai · retrieved 2026-08-03

How to cite thisCC BY 4.0 — reuse freely, attribution required

Plain

ModelRiskIndex. "Llama 4 Maverick LM Arena submission used unreleased experimental variant." Incident database, 2025-04-08. https://modelriskindex.com/incidents/llama4-lmarena-2025

BibTeX

@misc{mri-2025-04-08,
  title  = {Llama 4 Maverick LM Arena submission used unreleased experimental variant},
  author = {{ModelRiskIndex}},
  year   = {2025},
  note   = {Incident database, 2025-04-08},
  url    = {https://modelriskindex.com/incidents/llama4-lmarena-2025}
}

Please cite the dated entry rather than the site root. Every assessment here is a point-in-time judgment bound to evidence retrieved on a specific date — an undated citation asserts something the data does not.

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