For find queries we get PathArrayness in get_executor:
https://github.com/mongodb/mongo/blob/a401442a411faf56f2036d15503d16412578dc60/src/mongo/db/query/get_executor.cpp#L1187

The main reason for this is to do it after we already tried using express path and not slow it down with arrayness: https://github.com/mongodb/mongo/blob/909f2d4bf3324de44254cdb9286d15c54258c724/src/mongo/db/query/get_executor.cpp#L1174

This works fine, but feels a little bit too deep.