AWS Aurora MySQL Serverless CPU utilization is growing for unknown reason
What solved it for me was setting the min and max instance count higher than before (forcing aurora to scale up, for example from min 2 ACU to min 4 ACU), and after scaling restoring the scaling settings.

I used 'Force scaling the capacity to the specified values when the timeout is reached' and 'Apply immediately'.

It also solved another issue we had, the 'Serverless database capacity' indicated 4 ACU while it was actually 2 ACU (as seen in the picture)