This is similar to bug 380909 which was filed for K3b. Under wayland krusader only shows a general wayland icon and the Icon-only Task Manager doesnt recognize this(so an open krusader is shown as a new icon in the task manager)
Thanks for report. This was fixed in commit e396c209073d830dcb0d2e9eb7fab16f36fbbd8d (actually a day after 2.6.0 version tag). So in next Krusader version it will be fixed. I'm marking this resolved. Please feel free to reopen if you find this problem in git code (or in next version).