Regression in UX in the new shortcut added in T69868.
On wikis where edit summary is required or on any wiki where a user has forceeditsummary preference enabled ("Prompt me when entering a blank edit summary") the new "Save page" button doesn't work properly,
When the button is clicked the first time, nothing happens.
What really happens is that on the now-invisible panel for the edit summary a "Reminder:" is added, but this is not visible to the user. I imagine other error or warning scenarios (captcha, blacklist, abusefilter, etc.) may also cause issues here where the user is stranded.