Currently, the only way is to manually remove the tenancy context from the short URL, as you describe. We are similar to Kibana spaces here, where the context of the selected space is sent in the short URL.
One question: do RW users have a group configured, and an unrestricted user doesn’t have this group in a configuration, or is it a different case?
Short links created under the “basic user” cannot be opened by other users.
But if the “basic user” first opens admin short link, then he will have my tenancy in the url and at that moment all the links created by the basic user will work.