Yes profiles can severely affect the content of a build artifact and there is no way to tell the used profile in the Maven repo. This is generally the reason why it should not be used to influence the released build artifacts and can also not be relied upon.
Is it possible for a profile to materially affect what gets installed
in a repository, particularly the central repo?
I'm not concerned about minutiae like builds times and other details
the reproducible build work is concerned with. I'm talking about more
major things like which classes are and are not in a jar.
My gut is that this is possible because profiles can change plugins
and plugins can do pretty much anything. Assuming that's so, is there
a way to tell from the data in the repo which profile was used to
create a particular artifact?
I'm particularly concerned about dependencies. Profiles can change
dependencies, so the runtime and compile time classpath might depend
on the active profile.