(CC jtt@ as maintainer)
graphics/vtk should not expect parallel HDF5.
Fix for the upcoming hdf5-2.2.0 update:


Index: Makefile
===================================================================
RCS file: /cvs/ports/graphics/vtk/Makefile,v
diff -u -p -r1.16 Makefile
--- Makefile	26 Aug 2026 16:20:51 -0000	1.16
+++ Makefile	12 Sep 2026 19:55:00 -0000
@@ -7,6 +7,7 @@ COMMENT =		visualization toolkit
 V =			9.7.0
 DISTNAME =		VTK-${V}
 PKGNAME =		${DISTNAME:L}
+REVISION =		0
 
 .for LIB in vtkChartsCore vtkCommonCache vtkCommonColor \
 	vtkCommonComputationalGeometry vtkCommonCore vtkCommonDataModel \
@@ -97,6 +98,7 @@ LIB_DEPENDS =		archivers/lz4 \
 # ioss: part of seacas suite and difficult to package
 # token: a vtk utility
 CONFIGURE_ARGS +=	-DBUILD_SHARED_LIBS=ON \
+			-DHDF5_IS_PARALLEL=OFF \
 			-DVTK_FORBID_DOWNLOADS=ON \
 			-DVTK_VERSIONED_INSTALL=OFF \
 			-DVTK_BUILD_DOCUMENTATION=OFF \