My current employer (BigCo) has Terraform managing both infra + deployments in Terraform, at (ludicrous) scale. It's a nightmare. The problem with Terraform is that you must plan your workspaces such that you will not exceed the best-practice amount of resources per workspace (~100-200) or else plans will drastically slow down your time-to-deploy, checking stuff like databases and networking that you haven't touched and have no desire to touch. In practice this means creating a latticework of Terraform workspaces that trigger each other, and there are currently no good open-source tools that support it.

Best practice as I can currently see it is to have Terraform set up what you need for continuous delivery (e.g. ArgoCD) as part of the infrastructure, then use the CD tool to handle day-to-day deployments. Most CD tooling then asks you to package your deployment in something like Helm.