## Summary

When LiteLLM proxies an OpenAI-compatible embedding endpoint serving a model whose name does *not* contain `text-embedding-3` (e.g., a vLLM server hosting `Qwen/Qwen3-Embedding-0.6B`), passing `dimensions` in the request always raises `UnsupportedParamsError` regardless of `drop_params`. The raised error message instructs the user to set `litellm.drop_params = True` — but setting it has no effect on this code path. The only working escape hatch is `additional_drop_params: ["dimensions"]` per-model, which is undocumented for this scenario.

## Version

`litellm == 1.83.7` (also affects `main` at the time of filing). Running as a Docker proxy via `ghcr.io/berriai/litellm`.

## Where the bug lives

`litellm/utils.py :: get_optional_params_embeddings`, in the `elif custom_llm_provider == "openai":` branch — roughly lines 3300–3310 in 1.83.7:

```python elif custom_llm_provider == "openai": # 'dimensions` is only supported in `text-embedding-3` and later models if ( model is not None and "text-embedding-3" not in model and "dimensions" in non_default_params.keys() and "dimensions" not in (allowed_openai_params or []) ): rai…