Board Thread:Versus Debates/@comment-31338621-20200309130706/@comment-9782468-20200328182850

Is that not him just noticing that Itachi hit him with Tsukuyomi? With no other reaction from him between that instance and the end os Tsukuyomi, there's nothing to say the passage of time between that point and the end.

In any case, Zetsu made note of everytime Itachi seemed off or weaker or slower. He made no mention of Tsukuyomi taking longer than its usual second.