"Black" or "blank" screen after putting tab to fullscreen

pixelcow

pixelcow

Problem:

I see a "black screen" in each open window (no page, no menu etc., just the window-border)
The preview from the windows start-menu are black too

Situation

I have more than one opera-window open, each containing a few tabs
I can navigate tabs, with <Ctrl>+<Tab>, open/close them (I can see these changes in Windows 11's menu-bar when hovering above the Opera-icon)

What I did to get there

I put one of the tabs to fullscreen (pressing <F11>) and changed to another Opera-window with <Alt>+<Tab>
I worked in the other windows
going back to the fullscreen-window this one "got stuck" in fullscreen, couldn't click anything
going back to the other windows and changing tabs, testing fullscreen and going back, the window still was stuck in fullscreen, not responding. Trying to close it using <Ctrl>+<W> doesn't work in this window/tab!

What I tried so far:

I can press <F11> to put the black windows into fullscreen (and back) but this doesn't work BUT it at least restores the title-bar with the opera-logo to the left and the window-icons on the right including the window border.
I restarted the Windows 11 graphics-driver
I closed "all" running applications to free up RAM (read: all that I started myself after logging in like Notepad, File-Manager, Task-Manager)

What I need/want

I need to save my work or at least
bookmark the open tabs "in blind mode" as I can't see, where I click
Is there a way to see the open tabs somewhere so that I can at least write it up some information from there?
I opened some of the tabs in private-mode:
is there any chance to get entered data/cookies saved "manually" to get a chance of continuing where I left at least at some of the pages?

Side note:
No, there is no backup or whatsoever as I was reading some article and opened references and links from there for working on them in the office whilst on a long commute. I made a few quick notes in one of the browser-windows (can't find it) but it seems that didn't get saved, at least there's no update in the associated cloud-file (Google Drive - but this is more likely a completely different problem)

Software

Opera 105.0.4970.34
Windows 11 Home (latest automatic updates applied)