Increase the "My Group Hubs" list to more than 5?

As far as I can tell there's no configuration option for this OOB component (I'm also not aware of a setting within admin):

but if I remember correctly you can get all membership nodes (optionally for a specific node type, e.g. grouphubs in your case) for a user via API v2.0 like this:

SELECT * FROM nodes WHERE user.id = '<id>' AND node_type = 'grouphub'

EDIT: found the docs (gotta dig deep 😉) https://developer.khoros.com/khoroscommunitydevdocs/docs/membership-liql-examples