Comment 5 for bug 1905056

If you deploy a bundle that explicitly targets something, then juju will switch to that thing. Whether that is a different revision of a charm, or a different channel.
You can run 'juju deploy --dry-run' to see what Juju will do if you want to check first. And I can see possibilities around "change this from normal and pin it in some fashion that you have to unpin it in the future", but for now we don't intend to change this behavior.