I seriously doubt it is BaT. Too easy to prove if challenged, and it would destroy their business.
Seller-affiliated bids are far more likely.
Auctions don’t have any script or pattern. Bidders have different strategies or just may be dumb (see Hanlon’s Razor). Many throw out high bids early on what they’d pay, to test the waters, or to scare folks off. Or they may change their mind. Some wait until lot is going. Some hold back after initial bid betting on a better deal if RNM. Go look at the crap I got in BaT auction on my car for jacking the bid. I couldn’t follow closely that week & wanted to flush out the real interest. If it took off, I could ignore it. It didn’t & I got stuck at work during the auction close & couldn’t bid. Bought it after RNM. Other than auction terms, I have no duty to bidders, seller, BaT, or others’ sensibilities.
I do think seller-affiliated accounts bid, incl 1 recent E9 auction. But it isn’t always wrong, bad, or illegal, depending on state law and agreement terms. If I were king, unless prominently disclosed, seller-affiliated bids after reserve is met would always be banned as fraud. And they might be under CA law or terms. But super hard to enforce, esp online.