Should act() warnings be deduplicated by component stack?

React version: `16.13.1` (latest) and `0.0.0-7f28234f8` (next) ## Steps To Reproduce 1. Create component that has multiple effects (i.e. `useEffect` calls) 2. Render component in a jest test Link to code example: https://codesandbox.io/s/long-sound-xhe5w?file=/package.json ## The current behavior A error is logged for each call of `useEffect`. ## The expected behavior An error per component calling `useEffect`. ## Context Current errror: ``` Warning: An update to Component ran an effect, but was not wrapped in act(...). When testing, code that causes React state updates should be wrapped into act(...): act(() => { /* fire events that update state */ }); /* assert on the output */ This ensures that you're testing the behavior the user would see in the browser. Learn more at https://fb.me/react-wrap-tests-with-act at Component (https://xhe5w.csb.app/src/index.test.js:23:20) at App (https://xhe5w.csb.app/src/index.test.js:35:20) ``` The prescription is to wrap the update in act(). The warning may be unintented because a component with an effect rendered unexpectedly. But due to the rules of hooks it's unlikely that we remove a `useEffect` call: It's easier to prevent rendering a component (wrong branch logic, return early etc) than preventing an effect (which requires moving it to a component we render conditionally). From my experience most of these cases come down to adding an `act()` and not changing component implementation. In these cases firing errors for each effect makes the console output unreadable. Especially if you compose custom hooks and end up with 4+ effects per component. An alternate solution would be to only fire an error if the effect was actually scheduled (see #19318).