Breathwork activity counts on vibration cues to signal when one should breath in and out. The vibration is an integral part of the activity.
When DND is activated, the vibration cues no longer work. This makes the breathwork activity unusable. It is very often that this activity is practiced with the eyes closed, or just before going to bed. Without vibration there are no cues, no idea when to breath in or out.
One could argue that this was a design choice, but actually there are other vibration alerts that are still enabled when DND is on, like for example the vibrations when starting or stopping an activity. You would also want to have DND turned on, so that for example you don't get notifications that disturb you during this activity. So I am classifying this as a bug.
If this was implement by choice, there should be the option to enable vibrations during DND as otherwise this activity is useless for many.
