It's possible Windows 10 gives the virtual profile folder a custom icon but not the physical folder under C:\Users\ that it points to. I'm not entirely sure how that is configured or why Windows 11 no longer gives it an icon, to be honest. Opus just asks Windows for the icon to use for each folder.
If the Properties dialog can't change it, it can probably be done via the registry. On Windows 10, it seems to come from here:
HKEY_CLASSES_ROOT\CLSID\{59031a47-3f72-44a7-89c5-5595fe6b30ee}\DefaultIcon
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