You can actually specify maximum number of instances https://cloud.google.com/run/docs/configuring/max-instances as well as max requests handled by instance at a time (https://cloud.google.com/run/docs/about-concurrency).

From the article:

> The service will create more and more instances of your application up to the limit you defined

The docs confirm an instance maximum can be set and the price per instance can be less than $5/month.

It takes a lot of virality to go over $5/mo for a smaller-side project in Cloud Run. (essentially if you got the point where it would go over, the additional surplus traffic would be well worth it)

Or a $7 Heroku dyno if you don’t want to manage disks, networking, patching etc. and can afford the extra $2