جَاءَ ... رَأَيْتَ ... يَدْخُلُونَ
Came ... you saw ... they are entering. (110:1–2)
Jāʾa and raʾayta are past in form, whereas yadkhulūn is imperfect. The first two verbs set the event within the temporal-conditional frame of idhā; the imperfect makes the act of entry vivid as something unfolding before the observer.
This is more than a difference in conjugation: the discourse first establishes the situation and then animates it. Yet the imperfect alone does not claim unchanging rates of entry in every later period.