"Can this one become a problem?"

Good question and there is not a simple answer. Miscanthus sinensis has escaped cultivation and is considered an invasive species throughout much of the MidAtlantic states. But not all cultivars are created equally :-) Some culitvars produce a prodigious amount of fertile seeds, some produce almost none and others are considered to be sterile or at least self-incompatible and require cross pollination.

The Chicago Botanic Garden conducted an invasiveness trial and measured seed production. The results were summarized in this article from Fine Gardening.