Despite the signs some people still just sit and wait for passengers or worst still leave their car parked in the drop off area and walk to the terminal.
45 minutes with old charges = £38
45 minutes with new charges=£36
For anyone just dropping off 10 minutes is more than enough time with little queuing so the new price is just a price increase.
Compare
https://www.moneysavingexpert.com/news/2019/06/how-to-avoid-kiss-and-fly-charges/