Rear camera focus problems

Rear camera is having trouble focusing. It tries, but more often than not it seems to give up and everything is not quite focused.

I already opened up the unit and cleaned both sides of the window and used compressed air to clean the camera unit.

The window is not scratched, but it has developed some very small bubbles in the glass. It must be laminated and somehow its has developed some bubbles.

Wondering if these might be causing the camera to mis-focus.

Can the window be replaced? or you have to replace the whole backshell?