A small issue I’ve discovered:
When modifying a scheduled payment to a goal (that has been active for over a day), the “When” date is set as the original date that the scheduled payment was initially set up.
This means, that if you just change the scheduled amount and tap “Save” it will perform an immediate, and duplicate, payment.
Ideally, the date should automatically be set to the date of the next scheduled payment (the one displayed under the “Upcoming” details for the goal) so that changing the amount just effects the next scheduled payment, instead of making an extra, unexpected payment.
If you really wish to make an extra payment, this can still be easily done via the “Add Money” button for the goal.