When I've used Vivaldi, it has had some issues keeping its ducks in a row - the visual tab list shown to the user and the internal list kept by the browser can

When I've used Vivaldi, it has had some issues keeping its ducks in a row - the visual tab list shown to the user and the internal list kept by the browser can fall out of sync, which leads to all kinds of bizarre behavior when switching tabs with the keyboard. Tab stacks are the main reason why that happens. My guess is that Vivaldi just assigns the stacked tabs a flag rather than moving them together in the browser's memory.