Old terraform workspace suddenly having errors

Hi there,

I have a custom module that was last edited 4 years ago, in two workspaces that were last modified 2 months ago(infra is in a settled place mostly). The module is a wrapper around S3 and bucket policies that allows a single pane to grant cross account access, users,arns access to prefixes/etc. It's just worked for nearly the full 4 years.

However I recently went to make a change and I'm getting various '<x> value depends on resource attributes that cannot be determined until apply' errors. In workspaces that haven't had any code changes and last deployed successfully running them again gets the same errors as above.

I'm at a loss with how to debug it. Essentially we parse lists of objects passed into the module as variables and look at the arn structure to determine if the account is local/etc and use that in count values. It's all provided ahead of time and there are no data lookups. We're on a very old version of terraform but running on latest shows the same issue.

Using TF Cloud and last successful run was in December. Does anyone know of breaking changes to TF Cloud or TF, or suggestions on how to debug this. We have 50 or so usages of this module in place. Thanks!