In Amazon Web Services, each instance type has a different upper limit on how many Pods it can run. For example, an m5.large instance can only run 29 Pods, but an m5.4xlarge can run up to 234. The reason is that each EC2 instance can only have a limited number of IP addresses assigned to it.
https://medium.com/@mohamed.elmasary123/optimizing-pod-ip-allocation-in-aws-eks-with-amazon-vpc-cni-prefix-delegation-07d99004fdc2