On the shapely-2.0 branch, we have a failure on Appveyor (skipped at the moment), see #983 (comment), and some more analysis of @mwtoews at #983 (comment)

It might automatically go away when the source code of pygeos and shapely gets actually merged / usage of ctypes is completely removed, but in any case something to keep track off to check before final Shapely 2.0 release.