The user ID can be set through integrations, identify, or the create/update user API. However, after it's initially set, it can't be updated and will continue to show up on the user profile.

This is an issue if the initial source that set the ID is not the source of truth (i.e. set through HubSpot integration but the preference is having thee user ID match the company database instead).

Adding the ability to update the user ID after it has already been set will help ensure that it always matches the company's source of truth.