Credit limit and custom challenges

What is the daily credit limit, what is the point where we get deranked/removed credits, and do custom challenges effect the limit?

Also, can we turn in challenges before they’re completed to get a smaller amount of credits?

Cheers!

200,000 a day.
You went over the cap slightly, so it removed those extras.
Yes, they count towards the cap.
You can turn them in and get the credits it pays out, but you will not get any more for turning them in early, you can just make new challenges again earlier.