In the domain of survey design, we refer to these as points where people "drop" out. Surveys are likely more linear in design than an app, even with branching s

In the domain of survey design, we refer to these as points where people "drop" out. Surveys are likely more linear in design than an app, even with branching sections, but you might be able to chart out a general flow of actions that you need a user to go through and their linear sequence. Then summarize the number of users for whom each action was the last one that they completed of the full sequence. You'd then infer that the user dropped out due to something between doing the actions with the highest numbers and the very next action(s) in the chain.