jepp.. watch does its 'ding'-noise, i raise my arm to have a look at it and when i swipe the message down, it occasionally moves in sloooooow motion. Only seen this with mail notifications and could not tell, when this has started; i'd say, it began somewhere in watchOS version 5 or 6. Multiple updates and resets of the watch did not help. When switching to the Series 6, the watch was configured as new device to avoid this issue being 'restored' again.
As i see the issue as not very severe at this point, i did not reset and configure the phone as new device so far..