When you use your own custom private registry, you may end up using your own private CA signed or self signed certificates. This will cause container runtime to complain about untrusted cert, etc.
Here is a simple code that can fix this for you.
kubectl apply -f https://gist.github.com/yogendra/9937ead35a4ceb6f58ab5c4dc181cec3/node-ca-updater-daemons.yaml