As for Kaspersky Backup format and anti-rw protection... I see Kaspersky BackUps are saved to a special folder placed in C:\Backup, with special rights and I guess that, at least while Kaspersky protection is active, it will apply a strong protection and/or limit its rights to access.
In general I don't use such Kaspersky module/feature, I prefer to use others specialised tools for backup: Macrium Reflect Free and SyncBack Free

but I understand that for many average users can be a valid module/tool...