iSCSI mount with worng permissions in OpenShift 4

Issue

A StatefulSet that creates two volume mounts, one for an NFS PersistentVolume (datafile) and one for an iSCSI PersistentVolume (datablock).
NetApp Trident is the storage provider with a NetApp FAS providing the storage. The NFS PV is working fine, but the iSCSI one is mounted with the wrong permissions (irrelevant output omitted):

# cd / && ls -la
# drwxr-xr-x.   3 root root 4096 Jan  8 13:33 datablock
# drwxrwxrwx.   2   99   99 4096 Jan  8 15:39 datafile

The following user/group IDs are in the container which makes it impossible for the application to write to /datablock:

# id
# uid=1000610000(1000610000) gid=0(root) groups=0(root),1000610000

/datablock should be writable. This was working correctly on OpenShift 3.11.