Attestation Event stream emits less Attestation than expected

[InvisibleSymbol]

Describe the bug
For a project I'm working on I need a constant stream of all Attestations my nodes receives. After enabling --subscribe-all-subnets, this results in around around 900 Attestations/s being received.

But http://nimbus/eth/v1/events?topics=attestation only emits around 25-50 Attestation/s, seemingly a random sample of all received Attestations. This does not match what Teku does for example (emitting all), nor what I would expect the endpoint to do (a random sample is pretty useless).

To Reproduce
You can run this small script to get an Attestation/s count the endpoint emits. requires pip install sseclient

from sseclient import SSEClient
from tqdm import tqdm
for _ in tqdm(SSEClient("http://nimbus:5052/eth/v1/events?topics=attestation")):
    pass

[zah]

A fix for this has been merged in the unstable branch and will be shipped in Nimbus v22.6.0