Fargate isn't a competitor to Cloud Run (I wish it was) because it doesn't scale to zero in between requests and scale back up again when new traffic arrives.
It does scale to zero CPU when your application isn’t serving requests. See the pricing model at https://aws.amazon.com/apprunner/pricing/ for more details. It does not scale to zero memory, however, because customers have told us that cold-start latency has been their biggest pain point with Lambda functions. App Runner containers can respond to requests in milliseconds as a result.
Most of the stuff my company is running is made up of data pipelines and machine learning pipelines. So we have a lot of infrequent jobs that don't really care about latency.