After firefox-121.0-2.fc40 in both the gnome and kde task switchers (alt-tab) firefox doesn't have it's normal icon anymore. In kde it seems to pick some strange 'W' icon, not sure from what app. In gnome it has some untitled document icon. Probibly something to do with the new proxy cache? Reproducible: Always
Dupe of Bug 2255374. *** This bug has been marked as a duplicate of bug 2255374 ***