I've noticed this too. I think it is because the settings no longer include user-determined options for when the form runs. The form now runs automatically EVERY HOUR, in addition to when a new submission is detected, which means Google is recognizing the form run as an update or change even when no changes are made.
All of my forms with Doc Appender are now at the top of my Recents because they are updated on the hour. Super annoying. I'm guessing this takes up processing power somewhere too. Used to run just when new entries were submitted, which worked great.