Incorrect worker runtime specified for function app

[ThomasArdal]

I have received an email with a recommendation for one of my isolated functions with the following text:

We've noticed that your function app (my function name) is configured with the FUNCTIONS_WORKER_RUNTIME setting as "dotnet-isolated", but expected value for the deployed application payload is "CSharp". This is an unoptimized state which limits performance and may impact application reliability. To help detect this, you may now see the AZFD0013 event raised at the Warning level in your logs. This will be raised to Error level in a future update. To ensure your app can run properly, for its current payload, you should set the FUNCTIONS_WORKER_RUNTIME value to "dotnet". You must also update any deployment automations you have, such as templates or CI/CD pipelines, so they specify the correct value as well. Please see https://aka.ms/functions-invalid-worker-runtime for more information.

I don't think I understand what the problem is, even after reading through the content of the link provided. My function app is indeed marked with dotnet-isolated in the FUNCTIONS_WORKER_RUNTIME variable on Azure. The app is a C# based application with configuration looking like this:

<TargetFramework>net8.0</TargetFramework>
<AzureFunctionsVersion>v4</AzureFunctionsVersion>

Did I miss anything there? All of my other isolated function apps are configured this way and have been running without warnings so far.