It appears you still have the sadness in first Jhana.
What sort of sadness it is?
The Vitakka and Vicara in First Jhana are wholesome. That is loving kindness thoughts and renunciation thoughts which cannot be leading to sadness.
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While a mendicant is meditating—diligent, keen, and resolute—the faculty of sadness arises. They understand: ‘The faculty of sadness has arisen in me. And that has a foundation, a source, a condition, and a reason. It’s not possible for the faculty of sadness to arise without a foundation, a source, a condition, or a reason.’ They understand the faculty of sadness, its origin, its cessation, and where that faculty of sadness that’s arisen ceases without anything left over. And where does that faculty of sadness that’s arisen cease without anything left over? It’s when, as the placing of the mind and keeping it connected are stilled, a mendicant enters and remains in the second absorption, which has the rapture and bliss born of immersion, with internal clarity and confidence, and unified mind, without placing the mind and keeping it connected. That’s where the faculty of sadness that’s arisen ceases without anything left over. They’re called a mendicant who understands the cessation of the faculty of sadness, and who applies their mind to that end.
Bhikkhu Bodhi translates it as displeasure not sadness. So it could be seen as a vedana (unpleasantness) situation rather than a sankhara (sadness) situation.
About your comment “The Vitakka and Vicara in First Jhana are wholesome” I’m not sure about that. Have you got some sutta references to support it?
What about Karuna? Witnessing the suffering in the world - even while knowing this is the way things are. Direct witnessing of suffering does arouse compassion, which requires an understanding of the nature of suffering being experienced by another…
How is that relevant? Some fabrications are wholesome and others are not. For example, the four jhanas and the five nivaranas are fabricated. The jhanas are wholesome and the nivaranas are not.
According to Wikipedia, “Sadness is an emotional pain associated with, or characterized by, feelings of disadvantage, loss, despair, grief, helplessness, disappointment and sorrow.” Those don’t sound like mental activities that could take place in a state of jhana.
So yeah, translating it as displeasure or unpleasantness seems to make more sense. And, as has been noted, even the unpleasant vedanas cannot occur during the other jhanas.
I someone were to focus on the impermanence of mental states in the jhana, and in being dedicated to it, there were to realise unsatisfactoriness they might experience some unpleasant mental state while experiencing that realisation. In non-jhanic states, there is renunciate sadness. This is non-sensual and arises when the practitioner thinks ‘I have yet to attain nibbana’… The Buddha even says if a mendicant continues to uphold his life as a mendicant even with tears in their eyes (paraphrasing) it would still be wholesome. Insight practices can lead to disenchantment which is also unpleasant and has been recently called the dark night of the soul but is a advanced state of progress. Despite Abhidhamma (admittedly not the most favoured of my texts) going black and white on the dhammas, reality isn’t that ‘simples’.