Move files from Android to Windows PC leaves files on phone

What's the basic reason why when you "cut" a file or files from an Android device it just copies it and leaves the file still on the phone itself?

This happens on my Android version 11 phone. Is there a configuration needed to make sure that when files are "cut" from phone to PC with will not stay on the phone?

In general you cannot file-cut/paste to a different partition or device.
Cut just doesn't work that way, it's designed to simply re-allocate the directory information, the data itself never moves.

Across devices or partitions you would first have to write the new data then delete the old, as two separate steps. This is a Move rather than a cut/paste.
On Windows you can initiate this by right-click/drag the data you wish to move & selecting 'Move here' from the contextual menu when it appears

I can't test this will work when dragging from an Android device.