[Bug] subscribe_blocks could not downcast to pubsub when creating provider using RetryBackoffLayer

[chain-lover]

Component

provider, pubsub

What version of Alloy are you on?

0.9.2

Operating System

Linux

Describe the bug

I'm trying to build provider using RetryBackoffLayer as it was in the example below but adding IpcConnect:
https://github.com/alloy-rs/examples/blob/9db483f94af1fb23141baa8e574f3c2ae12b90e6/examples/layers/examples/retry_layer.rs#L29

It doesn't downcast to pubsub when running subscribe_blocks method.

struct ProviderConfig {
    ipc: String,
    max_rate_limit_retries: u32,
    initial_backoff: u64,
    compute_units_per_second: u64,
}

#[cfg(test)]
mod test {
    use alloy_provider::{IpcConnect, Provider, ProviderBuilder};
    use alloy_rpc_client::RpcClient;
    use alloy_transport::layers::RetryBackoffLayer;
    use anyhow::Result;

    use crate::aggregate::ProviderConfig;

    #[tokio::test]
    async fn should_stream_block() -> Result<()> {
        let provider_config = ProviderConfig {
            ipc: "/tmp/reth.ipc".to_string(),
            max_rate_limit_retries: 1,
            initial_backoff: 50,
            compute_units_per_second: 1600,
        };

        let ipc_connect = IpcConnect::new(provider_config.ipc);
        let retry_layer = RetryBackoffLayer::new(
            provider_config.max_rate_limit_retries,
            provider_config.initial_backoff,
            provider_config.compute_units_per_second,
        );

        let rpc_client = RpcClient::builder()
            .layer(retry_layer)
            .ipc(ipc_connect)
            .await?;

        let provider = ProviderBuilder::new()
            .disable_recommended_fillers()
            .on_client(rpc_client);

       let block_stream = provider.subscribe_blocks().await?;
        // Error: subscriptions are not available on this provider

        Ok(())
    }
}