Darktable version 3.4.1, I detect changes in the interface.
In the darkroom mode, it is worth viewing only images of a certain rating (in this case, without a rating), everything with which the processing is completed is sent out of sight either to be deleted or to its own group. Previously, there was auto-switching to the next frame, but now the image is deleted only from the filmstrip, and until you manually press the spacebar or click with the mouse, the transition to the next one will not occur, you will still work with the current one.
How to fix? Pressing two buttons is very annoying.