Due to handling an "offset spread page" change as if the "double page" mode got activated, the index of the secondary page was set, which resulted in opening the next page
Depending on the screen size and e.g. the set "reader width" pages might not have filled out the full img elements size due to "object-fit contain".
This was caused due to the image wrappers flex container "align-items center" which slightly reduced the images width to some ".xy" number (e.g. instead of wrappers width 258px, the images were something like 257.83px)
In case the last page of a manga was immediately visible or the became visible after the "image spread state" change, the chapter never got marked as read
Due to the way the pages got scrolled into view, the current page was not changed to the new page.
This then prevented the previous/next page to get opened via click/hotkey actions
