RFC 9002 [1] states that:

> Sending multiple packets into the network without any delay between them creates a packet burst that might cause short-term congestion and losses. Senders MUST either use pacing or limit such bursts. Senders SHOULD limit bursts to the initial congestion window; see Section 7.2.

We don't use pacing, and we don't limit bursts. Bursts happen every time the client resumes sending after an idle period, for example when sending a new request after being idle, or when resuming sending after exhausting the peer's receive window.

[1] https://www.rfc-editor.org/rfc/rfc9002.html#name-pacing