I found the link to these through Geoff Krall’s prbl curriculum maps (these are great by the way but it takes some time to learn where everything is as we don’t do grades the same way and we don’t necessarily teach things in the same order).
Anyway, I found this Nrich.org poster and there’s loads of them!! One a week for the rest of the year I think. They really are fantastic, properly challenging without being too confusing for students.