Running an effect only on update vs Strict mode

I have written a variation of the useEffect hook that should only run on updates. I used a useRef hook to accomplish this the way the FAQ in the old docs recommends it here:

I couldn't find the same piece in the new documentation.

The problem is that the effect still runs on the initial render when strict mode is on:
https://codesandbox.io/s/delicate-lake-88phjz?file=/src/App.js

however it behaves correctly when the strict mode is off:
https://codesandbox.io/s/hungry-wright-tl7p43?file=/src/App.js

In the former example the message is logged to the console right away even though it shouldn't be.

The possible explanations I can think of are:

1. I'm doing something wrong. Can you please point the mistake out for me?
2. The old docs are off and this is not the right way to do it. In this case can you please let me know what the right way of achieving this behavior is?
3. The strict mode is to blame. I do find it irritating at times, if I'm frank, but that's probably unlikely.

Can someone help me with this? Thanks a lot!

Start by reproducing the behavior in the two linked CodeSandbox examples, comparing the Strict Mode and non-Strict Mode cases. Read the current useEffect and useRef documentation alongside the old FAQ excerpt; done means the recommended behavior for effects that skip the initial render is clearly documented or the issue is explained as expected Strict Mode behavior.