I must add, i also installed rethink dns on an android box which has no gos and has android 7 and google play stuff as well and on that box the same thing was also happening.
I dont think its rethink dns per se however, because this is happening with other vpn and firewall apps too, as other people have reported.
I think the issue may not be a graphene issue, but an android issue.
The problem with the "Apps" app also giving errors on update is a separate issue and seems to occur on different vpn/firewall apps as people with different apps have reported the same.