This patch release has been tagged a while ago but its release was delayed. The main fix is to make the following corrections on the CRD schemas that were changed in v0.4.0 mistakenly:
vpcid->vpcIdvpcidRef->vpcIdRefvpcidSelector->vpcIdSelector
If you're on v0.4.0 and have used the incorrect vpcid, vpcidRef and vpcidSelector fields, after updating to v0.4.1, you will see those fields being gone from your instances. So, before updating, make sure you save all your YAML files using kubectl get managed -o yaml.
If you created your instances directly, then adding the same information with the new field name will be enough for migration, i.e. rename the field name and re-apply. If you use composition, changing the field name in the template will let Crossplane apply those resources with the new field and complete the migration.
During the process you may see some reconciliation errors complaining about vpc information missing.