Update: Opera One (version: 107.0.5045.21)
Chromium version: 121.0.6167.160
I think this was fixed already with the latest update (today). At least i can't reproduce same issue on YouTube anymore by pressing page buttons or a video, new window of Opera doesn't pop-up anymore.
I'll let you know if similar issue\problem will happen again.

Having a weird issue after latest update:
after launching browser, when i open youtube and click on any button on that page, Opera opens a second window with speed dial. After closing second window this does not happen again until closing the browser, launching it and doing the same thing again - opening youtube and click on any button (on page), a second browser window will open again.
Same happening even if i start Opera in Private Window.

Is there any way to fix this behavior without reinstalling the browser?

A few months ago, a similar problem already occurred after an Opera update, but then, when starting the browser, a second window opened immediately. Then I had to reinstall the browser to get reed of it, but I don’t want to do it again because of a bunch of settings, bookmarks, extensions (I tried disabling all of them, but it didn’t help), etc.

Linux, Nobara39, Gnome (45.3)+Wayland, Kernel version 6.7.0-204.fsync.fc39.x86_64.
Opera installed from repo https://rpm.opera.com/rpm

ps. btw Why hasn't Opera solved the problem with codecs yet? Why should users bother with replacing some files themselves so that they can watch videos and online streams? Aren't these basic functions that should work out of the box?

@zelgar hey! did you use this one: nwjs-ffmpeg-prebuilt
version 0.84.0? If not or you are using an older version, then try this one. I'm asking this because I had a similar issue with version 0.83.0.

Update: Opera One (version: 107.0.5045.21)
Chromium version: 121.0.6167.160
I think this was fixed already with the latest update (today). At least i can't reproduce same issue on YouTube anymore by pressing page buttons or a video, new window of Opera doesn't pop-up anymore.
I'll let you know if similar issue\problem will happen again.

add. info from "About Opera" window:
Opera One (version: 107.0.5045.15)
Update stream: Stable
Chromium version: 121.0.6167.140

From one of the threads on r/operabrowser another user has the same browser behavior\issue on Fedora Linux as mine right now and earlier (4 mo. ago).
Still waiting for next update or advice how to fix it (without reinstalling or resetting Opera with Recovery option) because if this is not fixed now, i'm sure it will happen again in the future after another update.

Having a weird issue after latest update:
after launching browser, when i open youtube and click on any button on that page, Opera opens a second window with speed dial. After closing second window this does not happen again until closing the browser, launching it and doing the same thing again - opening youtube and click on any button (on page), a second browser window will open again.
Same happening even if i start Opera in Private Window.

Is there any way to fix this behavior without reinstalling the browser?

A few months ago, a similar problem already occurred after an Opera update, but then, when starting the browser, a second window opened immediately. Then I had to reinstall the browser to get reed of it, but I don’t want to do it again because of a bunch of settings, bookmarks, extensions (I tried disabling all of them, but it didn’t help), etc.

Linux, Nobara39, Gnome (45.3)+Wayland, Kernel version 6.7.0-204.fsync.fc39.x86_64.
Opera installed from repo https://rpm.opera.com/rpm

ps. btw Why hasn't Opera solved the problem with codecs yet? Why should users bother with replacing some files themselves so that they can watch videos and online streams? Aren't these basic functions that should work out of the box?