SourceGenerator breaks build ?

[softlion]

I switched from the reactivemarble's propertychanged to the source generator version.
But now i'm getting this build error:

D:\MyApp\ReactiveMarbles.PropertyChanged.SourceGenerator\ReactiveMarbles.Proper
tyChanged.SourceGenerator.Generator\PropertyChanged.SourceGenerator.Extensions.cs(270,28): 

error CS0122: 'ObservableCollection<MyClass>.PropertyChanged' is inaccessible due to its protection level [D:\MyApp\MyApp.csproj::TargetFramework=net8.0-ios]

Any clue ?