llama 3.3 70b q4_k_m - tested on json schema with lots of nested oneOf constraints
perplexity holds to 20.6k then spikes when you have oneOf validators nested 4+ levels deep. model starts choosing the wrong schema branch and hallucinating fields that don't exist in any of the oneOf options. tested on openapi specs with discriminated unions. the failure mode is it loses track of which branch it's in and mixes fields from multiple branches
tested this exact schema pattern with postgres tool yesterday - json schema with 5 levels of oneOf constraints (query builder config that branches based on operation type). iirc the model holds fine to around 19.8k tokens then starts picking the wrong oneOf branch when nesting gets deep. perplexity doesn't spike much (maybe 2.1%) but the actual selection logic breaks - it consistently picks the first branch regardless of the discriminator field value. could be wrong but seems like the oneOf resolution degrades before perplexity shows it