No. If you're an active Setapp member, your subscription price won't change and will stay the same as it was in your first payment.
Similarly, if you successfully resolve a billing issue during the grace period, the price of your plan will stay the same as it was before the grace period.
New prices only apply to new Setapp members. However, if you decide to reactivate your subscription after canceling it, you'll be charged with the currently listed plan price — which might be different from the one you'd pay before termination.