たこすけさんお知らせありがとうございます
Opera 93.0.4585.37 Stable update

There you’ll see three sidebar options: on, off, and autohide.
We’ve also updated Opera 93 with the new Chromium version 107.0.5304.122. You can view the full changelog for all the changes.

関連
https://noushibou.hatenadiary.jp/entry/2022/11/25/082629

隠しても微妙に細い帯を表示して存在をアピールしてるのね