You seem to be the only person experiencing it.
So, I'm totally getting this now too.
Console output when I joined the server
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
CUtlLinkedList overflow! (exhausted index range)
CShadowMgr::AddShadowDecalToSurface - overflowed m_ShadowDecals linked list!
Possible something to do with it, but maybe a personal thing and I'm dumb, not sure.