how to avoid that firefox opened for first time icon is showed on every desktop in task manager

when I open firefox for the first time after boot the icon is showed on every desktop in task manager
the task manager settings are these:
show only tasks from current desktop and from current activity
in this picture firefox is opened in desktop 5 but I can see it in the task manager even if I am on other desktops, how to avoid this?
I tried other browsers like chrome, chromium and brave and they don’t behaviour like firefox

As you talk about a “task manager”, I assume this belongs to a desktop environment. But you do not explain which one. Like last year, we are not clairvoyant.

Then it’s likely the MozillaFirefox-branding-openSUSE package, switch to MozillaFirefox-branding-upstream and see if it duplicates.

you are righe as the last year, I’m not so used to consider that exists other desktop environments, I’m on KDE;)