Thank you for reaching out to us! I would be happy to provide some context!
When an app is created, it creates an OAuth ID in your Project, and only 30 OAuth ID's are possible per Project. Your Firebase Projects are connected to your GCP account, and the limits that it adheres to. Firebase allows a typical user 5-10 Projects per org, however that quota can be increased upon request following this guide.
The team that staffs the other end of those tickets is very expedient and should raise your quota quickly, however feel free to reach back out to me if you run into any stops.