I received a report from the Synonym team that slashtags auth on SN was not working on August 7th. I have not been able to fix it after attempting to.
When I reached out for help they let me know they are overhauling their auth system:
We have a new Auth library that works over relays and it will make things significantly easier to use and run - should be coming out soon
If you're only logged in via slashtags, please add another auth method. I don't know when we'll be able to get auth via slashtags working again.