I posted this as a reply to a different part but thought it may be useful here too.
I may have found a cause for the extra Lifestyle/Settings (Mode) Do Not Disturb and a way to stop it:
Check the Sleep mode on Bixby Routines. I found this has a setting within it that turns on Do Not Disturb and the mode is set by default to activate automatically. I turned off the automatic activation and this seems to have stopped the weird new DND settings appearing.
Hope that helps everyone.