Index containing types from DynamicContentModelsAssembly (13.2.8)

I have started seeing weird types in the index:

MyProject.Web.Features.Product.Models.DefaultVariationContent_DynamicProxy, DynamicContentModelsAssembly

I also have the correct type indexed, which is:

MyProject.Web.Features.Product.Models.DefaultVariationContent, MyProject.Web

Might this be a bug? If not, how can I get rid of those DynamicProxy types?