This prior issue (#8290) seems to have not been completely fixed by this pull request (#8940). In the case where you have a [GenerateSerializer] attribute in a sub/child namespace, only the top level namespace has the #pragma warning disable CS1591 and #pragma warning restore CS1591 added to it. I believe this may be due to this line?
Assume you have a namespace TheThing.Services and also TheThing.Services.Abstractions.Exceptions, both of which contain classes for which code will be generated. Only the first namespace, TheThing.Services, will have the pragma generated. None of the child/sub namespaces will have the pragma.
@ReubenBond