Don't apply modifications which break applications
On KDE, modifying the icon sets of GTK applications can result in them breaking. This is a common issue with Libadwaita applications, which show a warning icon instead. Apparently it happens with pure GTK applications too, so not a libadwaita-specific thing.
Applying the breeze-gtk theme also makes applications not look as the developers intended, and looks off. It in no way makes them blend in well with KDE.
Ideally KDE wouldn't set these modifications by default, just to name a few. If the user wants to enable these, they can do so themselves, with a warning that it can/will break applications and the UX. If this is an issue with downstreams, then I can migrate the issue to some (mainly Fedora).
Edited by Dallas Strouse