Not sure of any of the exact mechanisms behind the type 2 RTA syndromes but one can assume that all the nephrotoxic things listed under fanconi syndrome in first aid cause damage to the prox tubule first due to its high energy requirement for reabsorption. Loss of bicarb and subsequently RTA2 falls into that category
That’s literally all you need for step 1. We aren’t taking nephrology or path boards yet my friend. Don’t over think it