Terraform module for a Compute Engine VM Instance in GCP
First make sure you've planned & applied v2.6.0. Then, upon upgrading from v2.6.0 to v2.7.0, you may (or may not) see a plan that destroys & creates *_iam_member resources. It is OK to apply these changes as it only changes the IAM permissions from project-wide accesses to resource-specific accesses. Note that, after you plan & apply these changes, you may (or may not) get a "Provider produced inconsistent result after apply" error. Just re-plan and re-apply and that would resolve the error.
First make sure you've planned & applied v2.5.1. Then, upon upgrading from v2.5.1 to v2.6.0, you may (or may not) see a plan that destroys & creates an equal number of google_project_iam_member resources. It is OK to apply these changes as it will only change the data-structure of these resources from an array to a hashmap. Note that, after you plan & apply these changes, you may (or may not) get a "Provider produced inconsistent result after apply" error. Just re-plan and re-apply and that would resolve the error.