I have been installing and uninstalling QGIS (different versions) yet they are not displaying features symbols/styles in the symbology. I am using a HP ELITEBOOK core i7, 8 gen, Windows 11.
What might be the issue?
Try clicking on the "All" tab in the style manager. I notice you are clicked on the "Favorites" tab in the image, and if you haven't saved any favorites, it might not show anything.