This seems like it started "two updates ago"-- the X is not visible on the inactive tabs once you go past a certain number of total tabs. It seems like this is a gradual problem-- with just a few tabs, all tabs work as expected (you can close inactive windows without bringing them forward). With a medium number of tabs, the X's are missing, unless you slide over the inactive tab and enter it from the right, and then the X appears. And then with the situation as shown in the image, there's no X's at all, except for on the active tab.
This seems both like new behavior, and is unexpected.
I do have extensions, but none of them should affect the tabs (should)-- included screenshot.
I am running Windows 11 (10.0.22631.3296).
I believe my Opera is 108.0.5067.40.
My machine is AMD 7950X, 96GB RAM, 4TB SSD (Opera's install volume).

This seems like it started "two updates ago"-- the X is not visible on the inactive tabs once you go past a certain number of total tabs. It seems like this is a gradual problem-- with just a few tabs, all tabs work as expected (you can close inactive windows without bringing them forward). With a medium number of tabs, the X's are missing, unless you slide over the inactive tab and enter it from the right, and then the X appears. And then with the situation as shown in the image, there's no X's at all, except for on the active tab.
This seems both like new behavior, and is unexpected.
I do have extensions, but none of them should affect the tabs (should)-- included screenshot.
I am running Windows 11 (10.0.22631.3296).
I believe my Opera is 108.0.5067.40.
My machine is AMD 7950X, 96GB RAM, 4TB SSD (Opera's install volume).