How do I disable auto full screen in Opera on Mac mini with macOS Tahoe?

Is there any way of removing the annoying 'full screen on-click' one has no control of?

I only click anywhere and get full screen on Opera Browser. Then have to go through resizing as I have panes open I want to transfer data to.

Thanks.

[Re-Titled by Moderator]

Original Title: Tahoe on 2020 mini M1