I like the idea to be able to switch to spend points automatically.
May I suggest that you add another switch to allow automatically use points ONLY if the transaction is not one of the selected points earning merchant?
That’s what stopping me turning on “auto spending points” as it means I will miss opportunities to earn points if instead it choose to spend it with merchant I can earn.
This way, users can have full control of and at the same time least fiddling with the settings.
Also, would be good if we can set hierarchy of underlying cards. This allow users to have finesse control over the spending on which card with least amount of fiddling.