### Summary

When the Redis-backed parallel request limiter cannot read or atomically acquire a slot, it falls back to an in-memory counter in the current process. In a multi-pod deployment this changes one configured global limit into an independent limit per pod

### Current behavior

`litellm/proxy/hooks/parallel_request_limiter_v3.py` uses Redis for the shared gauge and Lua acquisition. On exceptions it logs a warning and calls `_acquire_parallel_slots_in_memory()`

The in-memory fallback is process-local. With a configured limit of `N` and `R` proxy replicas, Redis failure can allow approximately `R * N` concurrent requests instead of `N`. A deployment with no Redis configured is a separate supported local-only mode; this issue concerns a deployment that configured Redis for cross-pod coordination and then loses Redis availability

### Reproduction

Configure a model or global parallel request limit and run two or more proxy replicas with Redis enabled

Inject Redis failures for both the gauge read and the atomic acquire:

~~~python redis_client.eval = AsyncMock(side_effect=RuntimeError("Redis unavailable")) redis_client.get = AsyncMock(side_effect=RuntimeError("Redis unavaila…