Was more likely an abrupt descent of about 2000ft (with maybe a short peak ROD in the 6000+ fpm range).
They were steady FL250 when this first 'event' occured, 10 minutes later while cruising at FL290 they had a second deviation (descent) of about 800ft, followed minutes later the U-turn to return. So something certainly was not quite right, but apart from a bit of a rollercoarster for the pax at the first event, nothing overly spectacular, I presume.
Topic title has a bit of a tabloid flavor
