If HashiCorp is unwilling to switch Terraform back to an open source license, we propose to fork the legacy MPL-licensed Terraform and maintain the fork in the foundation. This is similar to how Linux and Kubernetes are managed by foundations (the Linux Foundation and the Cloud Native Computing Foundation, respectively), which are run by multiple companies, ensuring the tool stays truly open source and neutral and not at the whim of any one company.
Seems to me that Hashicorp forked Terraform by altering the license in a way that many (most?) contributors aren’t on board with; and OpenTF is the mainline now.