Blender 2.83.4 'save' error


I wonder if anyone else has encountered an issue when saving a blend file? Having just recently installed the 2.83.4 version and embarked on a new project, I’m finding that when saving my work there’s an error message appearing intermittently along the bottom of the interface telling me Blender “cannot change old file (saved with @)”. I don’t recall seeing this in previous versions.
I haven’t worked out whether there’s any consistency with this error appearing - it seems random. The end result is that a separate blend file is created with a ‘@’ added to the filename.
Ultimately the file is being saved, which is the main thing.
Is this a bug or is there something about the correct save process that I’m unaware of?