Which corners are you referring to, specifically? There are some applications that use GTK components, those are styled seperately in the settings under "GNOME/GTK Application Style". They will never look exactly like a native KDE/QT based application, but you can get them closer.
Likely you had a lot of GTK apps included with Workstation, you could also look into Qt alternatives to replace them - for example Gedit does not conform in KDE, but Kate will.
If you wipe and start fresh with the KDE install, it will prefer Qt applications. So that may be a worth while endeavor. Once you are settled, there is no reason to not upgrade in place. My install has been upgraded in place since fedora 32.