The Standard menu Save button action was changed to a split-action. It was necessary to support the frequently more common use of cloud based storage.
The issue and objections are well covered in Bug 98745 - Bring back Save as singular .uno command where folks should note we have implemented an Expert Configuration option to revert to a single action local Save button for those that insist.
For releases 5.1 forward
Tools → Options → Advanced “Expert Configuration” session and searching
then edit the “controller” string replacing
on LibreOffice restart, restores the
non-split button behavior to the
Toolbar “Save” button.
Reverse steps to restore the Split button.
For 5.2 forward we have also provided a SIMPLESAVE button action that can be added by customization of the Standard toolbar.
tdf#96590 UI: save icon does not give a hint of the document status
tdf#97878 Failure of Save icon
tdf#98745 Bring back Save as singular .uno command
tdf#98779 UI: “single action” save icon doesn’t give a hint of the document status
Adding split Save button to Standard toolbar
Adding an optional “simple” Save button for customization use