That is not a trick, it’s called shill bidding and it’s illegal.
I suspect shill bidding happens more often than not with high interest items, but is basically undetectable. E-bay claim to monitor, but why do they care? they get their fee in any case (perhaps several times for the same item!). E-bay have no incentive to do anything, publish no information on their monitoring. E-bay is literally a closed shop apparently outside of any regulatory control.
In addition, you also have to contend with widespread use of sniping software so you never get any feel for how your sale is going until it closes. Always was a bit dodgy but now even more so and expensive too as charges getting up to near 15%.
It has its uses but use with care. If I list anything, it is at the minimum price I will accept allowing for fee and delivery. If it doesn’t sell, then there is no loss. If it goes for the start price, fine. Occasionally, I have even had a small premium on an item, but not often.