I would have thought anyone who held a BA gold card would have flown enough to know about the effects of thrust reversers.
Come on, time to 'fess up - how many flights have you really taken
As others have said, noise and vibration is normal, in fact some of us "of a certain age" will remember the PA from the cabin crew alerting pax to that there would be a lot of noise after landing and that this was normal.
The engines spool back up when reverse thrust is selected because the power needed is greater than idle
Sometimes idle reverse is used and this is hardly noticeable.