Unexpected enomem error during file downloading

[viralpraxis]

Hi there!

We tried to migrate from 1.18.1 to 1.20.1 and encountered increased error rate during downloading huge (~1GB) files.

I've published an MRE: https://gist.github.com/viralpraxis/6209746ee3b108473452ee810678f769
You can run it via mix run -e 'Runner.start($URI)', $URI points to a file over 1GB (serving over python -m http.server would be fine).

On 1.18.1:

21:47:47.878 [info] 2: Streaming completed
21:47:47.946 [info] 1: Streaming completed
21:47:47.990 [info] 5: Streaming completed
21:47:48.055 [info] 4: Streaming completed
21:47:48.066 [info] 3: Streaming completed

On 1.20.1:

21:48:12.494 [error] Error while streaming: enomem
21:48:12.494 [error] Error while streaming: enomem
21:48:12.494 [error] Error while streaming: enomem
21:48:12.494 [error] Error while streaming: enomem
21:48:12.494 [error] Error while streaming: enomem

In fact this error is reproducible on 1.18.2. I bisect'd this error to 5e74354 (previous commit e3872f7 works fine).

elixir 1.16.1
erlang 26.2.2

Please let my know if you need any addition information. Thanks!