Remove selected range: Inconsistent behavior involving key signatures

OS: Windows 10 (10.0), Arch.: x86_64, MuseScore version (64-bit): 3.1.0.6538, revision: 9924d9c

This isn't a regression. It was a feature of 2.3.2 (and before?) as well. See attached score.
1. Select the first measure and press Ctrl + Delete.
Result: The measure is deleted but the key signature remains.
2. UNDO. Now select the first 2 measures and press Ctrl + Delete.
Result: As before.
3. UNDO. Now select the first 4 measures (system 1) and press Ctrl + Delete.
Result: The measures are deleted but also the Key signature.
4. UNDO and this time select the first 5 measures (i.e. system 1 and the first measure of system 2). Press Ctrl + Delete.
Result: The measures are deleted but not the Key signature. It appears that the key signature is deleted only when you select to the end of any system.

Shouldn't the behaviour be consistent here?