How can the user know when a purchase was very high or atypical for their common spending habits?

This is a type 2 question because as developers, we can analyze the spending habits from our users in order to indicate them and answer to the question of how as an user can I know that I spent too much on something? and show them the answer through the UI in order to benefit the user experience and awareness of their habits.

How are we doing this?

Whenever the user has more than 5 transactions logged, the analytic backend con show if the transaction is atypical for the user. The way of showing this, is with an "💳" icon aside the transaction name. this way, the user can easily identify which are the transactions that are not common in their daily life.