@freelanceartist Oh yeap, that's exactly it. Sad to read there's no way to turn that off. In my opinion any changes to the user interface (especially new features) should come with a on/off toggle switch. I used to use Opera a lot in the past and just gave it another try a few days ago and was surprised about this.
There seems to have been some focus on the address bar recently, both firefox and chrome are now "growing" their address bar when it receives input, I guess Opera took it a step further and is changing the background colour also. I'm not saying it's necessarily bad but I fully agree with you, an option to disable it would be great.