I am not a developer and this is a suggestion based on what happened to me.
I created a Nextcloud instance with 12 people gave them all usernames that was just their name ‘John Smith’
As a result I cannot now mention them in comments as they do not appear, so I can’t do @John Smith - it doesn’t work.
And since there is no @John as a username I get @unknownuser
I think when someone creates the username - Nextcloud should not accept a user name with space in the middle.
If anyone has a fix for this I’d be interested - othere wise I need to delete 12 users and recreate them. Which seems to be a hassle.
Thanks for Nextcloud. I love it