Sorry to nudge you back, but I have been receiving notifications during the evening (not setting DND; more details below) and wanted to be sure: is SleepWear 5.23 using the alarm stream for the vibrations? (as described here)
I ask because setting bedtime or DND modes negates all but the first vibration, even if they both are set up to allow alarms. It could very well just be a bug from OnePlus, so I wanted to be sure this version of the app is doing things by the book when they get back to me on the support case.