beta and nightly ignore the default-on configuration of "Auto-hide trait implementation documentation"

On stable std::future::Pending looks like:

While on beta it looks like:

And on nightly (as of 2021-05-17):

Going to https://doc.rust-lang.org/nightly/settings.html and toggling "Auto-hide trait implementation documentation" off makes stable look the same as beta, so it definitely seems like beta/nightly are just ignoring this toggle.