Along with the new WordPress 4.4, theme and plugin developers are swiftly moving to upgrade their products. 22 plugin updates and 11 theme updates in the last two days alone. You shouldn’t notice any changes at this point.
One plugin, “Subscribe By Email”, was causing problems for people trying to sign up. If you were using it and weren’t getting any new subscribers, that’s why. We’ve transitioned all those blogs over to “Email Subscribers,” which is considerably more robust (meaning: it actually works). If you’ve got an active blog and think your audience might want to hear from you, consider activating it. It’s a simple matter of going into Plugins in your dashboard and activating it, then adding the widget.