As was reported on the German-language Wikipedia's feedback page, while there is a notification shown when switching from visual to source code editing, there is no such notification when switching back. Previously, such a notification was shown.

1. Log in with a new user account (older accounts usually have turned off these notifications)
2. Open a random article for source code editing
3. Use the pen in the upper right-hand corner of the editor to switch to visual editing

One would then expect to see a notification similar to the one below, but nothing is shown.