If you read the various discussions that I, @Sunyo, and others mentioned above you’ll see that this issue of whether the Buddha (or other practitioner) is *in jhāna during such experiences/insights has been hotly discussed. And, as Ven @Dhammanando indicates, it was also hotly discussed back at the Third Council.
Other examples are:
And also MN111:
He knew those phenomena as they arose, as they remained, and as they went away.
I don’t have sufficient depth of Pāli and other knowledge to make a useful contribution to the arguments about the timing issues: Whether the language really does mean that the insight occurs within the jhāna or whether they occur after emerging from the jhāna, while the mind is “purified, bright, etc…” (MN36)
When my mind had immersed in samādhi like this—purified, bright, flawless, rid of corruptions, pliable, workable, steady, and imperturbable—I extended it toward recollection of past lives.
“When my concentrated mind was thus purified, bright, unblemished, rid of imperfection, malleable, wieldy, steady, and attained to imperturbability, I directed it to knowledge of the recollection of past lives.
See also Ven @Kumara’s recent thread: My “Jhāna” Story
and Ven Analayo’s recent paper:
“A Brief History of Buddhist Absorption”, Mindfulness, 2020, 11.3: 571–586.
The final text is not available for free but the draft submitted to the journal is linked to here: Publications by Bhikkhu Anālayo. Specifically: https://www.buddhismuskunde.uni-hamburg.de/pdf/5-personen/analayo/briefhistoryjhana.pdf
Personally, I remain a spectator, following Ven @Dhammanando’s advice that I quoted above:
Dhammanando : As the disagreement doesn’t involve any difference of opinion over how the preliminary practice of samatha-bhāvanā is to be carried out, one always has the option of just going ahead with the work while maintaining an agnostic stance on the contested questions about what jhāna is like.