Tab stack are back, kind of. There should be option to "Move tab to Workspace X" in somewhere.

@leocg: I'm not sure what you mean. I think it's now opposite: workspaces are part of window even if same workspaces are available in all windows. When I create workspace the same workspace name is visible in all windows. But they are separate and that was confusing to me because I knew that certain tab lives in certain Workspace but when you have more than one window you should also remember in what window is the right one. I think I'm moving my multiple window-system to one window/multiple workspaces -system but nevertheless I think UI doesn't now tell that certain workspace in certain window is not at all related to another window's workspace with same name. Therefore I think could be better that moving a tab -option would show that you could move tab to workspace in another window too.
Also if I select multiple tabs there is option to move those tabs to certain workspace. I would prefer that scenario also should allow to move those tabs to certain workspace in certain window.

I like workspaces a lot but I would prefer that workspaces are universal across the windows. Or at least there should be easier way to move tabs around windows than drag and drop. My original set up was 3 windows and about 300 tabs and now I'm trying to achieve one window /multiple workspaces system but move to workspace moves it inside a window. I understand that logic but could be very useful to have Move to Workspace "Work" in Window 1 /Window 2 etc.

I would suggest to add option to give window a name too and then add possibility to Add to workspace of other window. I have 4 windows which contains plethora of tabs and arranging them using workspace is tempting but currently annoying -> drag tab to another window that contains desired workspace. For example I could have windows called Work and Joy and Surfing. Work could contain workspaces like Coding, Databases, Devices. When i am on Surfing window and find something to be checked later I could use menu to Move tab to Workspace Work\Databases

@louay-madanat You didn't ask for me but one of my reason is couple of hundreds of tabs. Transferring my precious session is not easy. I regulardy try Vivaldi but still like Opera more for my purposes.

Tab stack are back, kind of. There should be option to "Move tab to Workspace X" in somewhere.

Because of lack of tab stacks I've been using separate windows for separate things and I too often accidentally close one window instead of whole Opera and then I lost my fine tuned tabs. (And if I accidentally close second one I lost it permanently because there's no recent window -option after restarting Opera - that happened too.