The fact that the share price has fallen, would have resulted in...

The fact that the share price has fallen, would have resulted in margin calls for anyone long of a synthetic. If the margin call payment could not be met, the broker would be forced to sell out the long position.
In the case of Mini's some have a stop loss. When the price moves against you by a certain percentage they automatically get closed out. It is public knowledge where the stop loss is for these mini's. Someone with a view that the share price is going down would be aware of these "tipping points" and downside pressure on the share price below the stop loss would trigger forced selling.
Remember the same applies on the way up!!!
For all BRU shareholders buying leveraged BRU products to get additional exposure, remember that the stock purchased to hedge your position is being lent to the shorters. You are stoking the fire!