Azure App Service doesn't have .NET 6 installed

Question

I'm having some issues when trying to deploy an application that has been upgraded to .NET 6.
When I change the web app from .net core 3.1 to .net 6, it starts crashing.

If I downgrade it back to .net 3.1 then I can at least access kudu but I'm getting an error:
HTTP Error 500.31 - Failed to load http://ASP.NET Core runtime
Common solutions to this issue:
The specified version of http://Microsoft.NetCore.App or http://Microsoft.AspNetCore.App was not found.
Specific error detected by ANCM:
It was not possible to find any compatible framework version The framework 'http://Microsoft.NETCore.App', version '6.0.0' was not found. - The following frameworks were found: 1.0.16 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 1.1.13 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 2.0.9 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 2.1.26 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 2.2.14 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 3.0.3 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 3.1.13 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] 5.0.4 at [D:\Program Files (x86)\dotnet\shared\http://Microsoft.NETCore.App] You can resolve the problem by installing the specified framework and/or SDK. The specified framework can be found at: - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=6.0.0&arch=x86&rid=win10-x86

If I do a dotnet --version in the cmd prompt from kudu, I see the it's set to dotnet 5 and not 6. It also doesn't change if I install the runtime using the extensions. Please advise on how this can be fixed.

Thanks!

Here's a screenshot of kudu. It doesn't show .NET 6 and I can't install it. I tried it using the extensions but it doesn't work either.