I'm sorry but I really don't like this new design style for Opera. I'm not a fan of the rounded corners in Windows 11, and here they are again but even stronger - for me rounded corners make things look childish; and it's making the tabs, address bar and side bar a lot larger than they need to be, wasting screen space.
For tabs, I much prefer them to look like 'tabs', instead they now look like chunky buttons.
I think I'm going to have to look at other browsers. Such a shame. I really liked the previous version.