Terraform bug - sporadic changes to function app settings on redeploy

gistfile1.txt

Terraform will perform the following actions:

module.functions.azurerm_function_app.trafficdata will be updated in-place  ~ resource "azurerm_function_app" "trafficdata" {        app_service_plan_id            = "/subscriptions/xxxxxxxxxxxxxxxxxxxxxxxxxxxxx/resourceGroups/rg-xxxxxxx-test-traffic/providers/Microsoft.Web/serverfarms/plan-xxxxxxxxxx-traffic-test"      ~ app_settings                   = {            "APPINSIGHTS_INSTRUMENTATIONKEY" = "xxxxxxxxxxxxxxxxxxxxxxxxxxx"            "AZURE_MAPS_ENDPOINT"            = "https://atlas.microsoft.com/"

"BUILD_FLAGS"                    = "UseExpressBuild" -> null            "CITIES_CONFIG_URL"              = "https://xxxxxxxxxxxxxxxxx.blob.core.windows.net/config/cities.json"

"ENABLE_ORYX_BUILD"              = "true" -> null            "FUNCTIONS_WORKER_RUNTIME"       = "python"            "KEY_VAULT"                      = "https://xxxxxxxxxxxxxxxx.vault.azure.net/"            "NUM_OF_ROUTES_PER_CITY"         = "100"

"SCM_DO_BUILD_DURING_DEPLOYMENT" = "1" -> null            "TRAFFICROUTES_OUTPUT_URL"       = "https://xxxxxxxxxxxxxxx.blob.core.windows.net/trafficroutes"            "TRAFFICTILES_OUTPUT_URL"        = "https://xxxxxxxxxxxxxxxxxxxxx.blob.core.windows.net/traffictiles"            "WEBSITE_NODE_DEFAULT_VERSION"   = "~10"

"XDG_CACHE_HOME"                 = "/tmp/.cache" -> null        }