Yes, currently .NET 8.0 is not yet supported in Visual Studio for Mac. The latest version that is currently supported is .NET 7.0.
However, you can still use .NET 8.0 by using the .NET MAUI CLI tools instead of Visual Studio for Mac. You can install the CLI tools by running the following command in your terminal:
dotnet tool install -g Redth.Net.Maui.Cli
After installing the CLI tools, you can create a new .NET MAUI project using the following command:
maui new MyApp --template-blank
This will create a new .NET MAUI project using .NET 8.0.
I hope this help :-) Please mark my answer if it does.