Monthly cost management

Hello.

From the content of the image, it seems that you are using EKS and EC2, so how about purchasing Savings Plans?
Savings Plans is a pricing system in which usage fees are discounted by signing a contract for a specific amount of usage (determine how many dollars per hour you will use AWS) for a period of 1 or 3 years.
https://aws.amazon.com/jp/blogs/containers/saving-money-pod-at-time-with-eks-fargate-and-aws-compute-savings-plans/

You can also use Compute Optimizer to suggest optimal instance sizes for over-provisioned and under-provisioned instances in EC2, so following the instructions can lead to cost savings.
https://docs.aws.amazon.com/compute-optimizer/latest/ug/what-is-compute-optimizer.html

Since you only use a few services, you could explore individual cost optimization techniques for the features that you are using, to make sure that you are using them efficiently. A great resource I would recommend - check out our Cloud Financial Framework (CFF) for the services playbooks where you can find some tips: https://catalog.us-east-1.prod.workshops.aws/workshops/86e30fc2-daf4-4708-8720-347e2b312075/en-US/playbooks

I'd generally suggest checking out the CFF workhsop from the introduction part if you're interested to learn more about the basics (cost monitoring, cost visiblity, governance, etc...) - but even if you just check out the services playbook, you'll find a lot of useful information.

I'd like to also suggest what Riku_Kobayashi mentioned in their reply. First check if there's opportunity to rightsize (use smaller instances or more suitable type & family of instances) or maybe even use Spot if applicable to your application. If Spot instances wouldn't work for you, then explore reserving Savings Plans as they basically provide a flat discount for compute. You can use Savings Plans recommendations in Cost Explorer tool to see what's the recommended commitment.

I also see you have Data Transfer charges, check out in the CFF resource that I shared for any recommendations regarding best practices how to understand your data transfer charges.