Lambda source_code_hash value is updated for no changes in the zip file

Terraform Providers AWS
1

So, I am trying out TF v1.5 to import an existing lambda. I created the import block, ran plan and apply and it got imported to my state file. I re-ran the plan on the same files without changing anything, expecting that there will be no changes. But, the source_code_hash is showing changes. I assumed this would not change as there are no changes done since the last successful import. So, why is it showing a change in the plan?

resource "aws_lambda_function" "lambda_function" {
  filename      = "../../lambda/vpc-default-reporting.zip"
  function_name = "vpc_default_reporting"
  role          = aws_iam_role.lambda_exe_role.arn
  handler       = "lambda_function.lambda_handler"
  timeout       = "300"
  memory_size   = "2048"
  source_code_hash = filebase64sha256("../../lambda/vpc-default-reporting.zip")

  runtime = "python3.7"

  
  environment {
    variables = {      
      region = var.target_region
    }
  }
  
}

Plan output:


  "Terraform will perform the following actions:",
        "",
        "  # aws_lambda_function.lambda_function will be updated in-place",
        "  ~ resource \"aws_lambda_function\" \"lambda_function\" {",
        "        id                             = \"vpc_default_reporting\"",
        "      ~ last_modified                  = \"2023-06-23T06:10:30.691+0000\" -> (known after apply)",
        "      ~ source_code_hash               = \"Gq5Zz1uRRW9V5R0fbpaVsOvh0PzGQ1QC230MjdjRcSM=\" -> \"5BPzTMjO/ziAJpn1VXFnV8oQybR/VP4pg9LKVziUPLE=\"",
        "        tags                           = {}",
        "        # (20 unchanged attributes hidden)",
        "",
        "        # (3 unchanged blocks hidden)",
        "    }",
        "",
        "Plan: 0 to add, 1 to change, 0 to destroy.",
2

It appears the current code hash fetched from the AWS API disagrees with the content of your file on disk.

(And so Terraform plans to upload the local code to make them match.)