"beacon node misconfiguration" error on /eth/v1/events

[a26nine]

Describe the bug

When trying to subscribe to events with Prysm v5.1.2, the node throws misconfiguration error.

Flags

prysm \
    --accept-terms-of-use \
    --datadir=/data/prysm \
    --chain-config-file=/data/prysm/config.yml \
    --genesis-state=/data/prysm/genesis.ssz \
    --chain-id=xxx \
    --network-id=xxx \
    --execution-endpoint=http://127.0.0.1:8551 \
    --jwt-secret=/data/jwtsecret \
    --http-host=0.0.0.0 \
    --http-port=3500 \
    --rpc-host=0.0.0.0 \
    --rpc-port=4000 \
    --http-cors-domain="*" \
    --http-modules=eth,prysm \
    --bootstrap-node=xxx \
    --peer=xxx \
    --min-sync-peers=1 \
    --p2p-tcp-port=13000 \
    --p2p-udp-port=12000 \
    --p2p-max-peers=50 \
    --p2p-static-id \
    --slots-per-archive-point=32 \
    --blob-retention-epochs=1000000 \
    --api-timeout=30s \
    --monitoring-host=127.0.0.1 \
    --monitoring-port=8080

Execution Client: Geth v1.14.11

The node is syncing fine and responds to other methods without any issues.

Has this worked before in a previous version?

No response

🔬 Minimal Reproduction

1. Run Prysm v5.1.2 (with the above flags).
2. Call curl "http://localhost:3500/eth/v1/events?topics=head" -H "Accept: text/event-stream"

Error

{"message":"beacon node misconfiguration: http stack may not support required response handling features, like flushing","code":500}

Platform(s)

Linux (x86)

What version of Prysm are you running? (Which release)

v5.1.2

Anything else relevant (validator index / public key)?

No response

[james-prysm]

Is there possibly something else with your setup that may be different? cURL should be supported here

[a26nine]

Is there possibly something else with your setup that may be different? cURL should be supported here

I don't think or am aware of anything else that would be different here. You can see the node config in the OP. Plus, other Beacon API methods seem to work without any issues.