Docker sandboxes run `sleep infinity` as PID 1. `sleep` never wait()s on re-parented children, so Chromium's short-lived helper/crashpad processes accumulate as zombies in long-lived browser sandboxes. With `pids_limit` set, this eventually exhausts the slot and the container can no longer fork — the browser tool starts failing before it looks "unhealthy" anywhere else. Setting HostConfig.init = Some(true) makes Docker inject tini, which reaps re-parented children. Note: existing sandbox containers keep their old spec (init is set at create time). Cycle them post-deploy to pick up tini.