I see in the docs here:
https://qwik.builder.io/docs/advanced/dollar/
That the compiler is supposed to generate both onMount and onRender. However, I'm not seeing such behaviour on latest Qwik. As a result of that, it seems that useTask does not block the render phase, and indeed having an useTask handler causes the component to render twice in the server, even though the useTask only happens once.