A couple of possibilities.

also, possibly, "June drop"



Fruit set percentage and severity of fruit drop vary considerably among the major fruit crops. Fruit set may be as high as 90% for blueberries, 10-20% for apples and peaches to a low of 1% for sweet oranges. Moreover, blueberries have a small percentage of fruit drop after the initial fruit set period, while apples, peaches and citrus have a pronounced and sometimes extensive June drop. The severity of postbloom drop is a function of cultivar, environment, and cultural practices. Nevertheless, some degree of fruit drop is not only desirable, but necessary. For example, a mature navel orange tree may produce 100,000 flowers.
https://irrec.ifas.ufl.edu/flcitrus/pdfs/short_course_and_wo...


Also, 'postbloom fruit drop'
https://www.plantmanagementnetwork.org/pub/php/review/fruitd...