Warum wurde ein Foto abgelehnt?

If it's a technical issue, I think it's the white balance.
When looking at plants or people's faces, the colors tend to be yellowish.

Even if you correct the white balance, if there's text or logos on signs, it will be rejected due to IP issues.

Then I would say loss of detail in the highlights and shadows. In any event, moderators can only give one reason for a rejection, while there may in fact be a number of issues. And Adobe would for sure require a property release at minimum. The below example isn’t perfect, but it should give you an idea how exposure might be improved.

Did you submit a property release? Also, depending on the asset’s original size, some people might be identifiable. Did you obtain model releases?