If you’re a user of an insurance with downvotes disabled, you’re not able to downvote anything anywhere even on other instances, and you’re not able to see downvotes on anything from anywhere even other instances. Users from other instances can downvote on your content and content from others from your instance or posted from users from other instances on communities from other instances but are only visible to users from instances with downvotes enabled.
This has some unexpected effects besides only “hiding” the downvotes on your user interface, this affects sorting a little differently in those instances.