I want to roll back to specific version of kubernetes. My current version is 1.21. Is there any system specifications for kubernetes?
If you are using a managed service, you probably won't be able to roll back, and I would strongly recommend AGAINST rolling back even if you can.
Managed services like GKE, AKS and EKS will only allow you to pick from the latest couple of versions (normally between 3-4 minor versions), but will not allow you to downgrade a minor version (e.g. you can't downgrade from 1.21 to 1.20 for example see here for GKE example)
Rolling back a version will re-introduce any bugs and security issues that were fixed by the upgrade. So essentially, you are making your cluster less secure by downgrading.
Clients such as kubectl will also flag up skew warnings such as in this question, and the rolled back clusters will start rejecting deployments if you've already updated them for new apiVersions
For example if the version you migrated from had an API version something/v1beta and the new version required you to use something/v1 then if you tried to deploy a deployment on the rolled back cluster that used something/v1 (to meet the new cluster version), the rolled back cluster would reject that.