Let’s have a look at this Transaction.
I had 1.618RDD on my old address (Rb7qTBdcm8sDTVsjZeYjWPVcWYSN8qLNpa)
The blockchain technology doesn’t allow it to just send 18RDD and leave 1.600RDD where they are.
The whole amount have to be moved like a banknote.
You can’t just cut it in half and keep one piece.
Instead you give it as one piece away and receive a new banknote with a lower value.
But you have to specify per “coin control” where this new note (or 1,89M in your case) have to go or your wallet software will decide that on its own.
In my case 18RDD were sent to its target address (Rr2AyYfHnDwhNpauo4MYVsyU4TqF1ShNfA) and the rest of 1.600RDD are on a newly generated change address now. (Rbg67ChHQmqu18AeFyMy6Jbk3xvZbfhAoe)
I don’t know why it was not sent back to the old address but I think this has to do with some kind of tamper protection.
An old backup of my wallet has no way to know about this new address.
So i have to make a new backup or send the change to a previously known address.