I have created one assignment report by adding col..

I have created one assignment report by adding column ID. so when I am adding column ID and saving the report it is hitting some endpoint to get that values for that ID column . so now can anyone help me how to known what endpoint there are hitting to get those ID values as I want to store all those ID's in one file, if I known endpoint what there are hitting , I can use that endpoint and get all values of that ID column. Please help me in finding which endpoint they are hitting.