Haddocks for base-4.16.1.0 on Hackage are missing source links for instances
See e.g. the instances for Functor
at https://hackage.haskell.org/package/base-4.16.1.0/docs/Data-Functor.html#t:Functor. There are no links to the instance definitions in the hyperlinked source code.
In base-4.16.0.0 these links were present: https://hackage.haskell.org/package/base-4.16.0.0/docs/Data-Functor.html#t:Functor