Spoofing, wash trading, etc have always been common in crypto. Market microstructure is much more adversarial than most markets. If you have an automated strategy that uses and assumes orderbook data and execution data accurately represents market conditions, you will lose your money.
Most exchanges will have "liquidity partners" who have better fee structures, possibly even zero fees. Most of these arrangements are not publicly disclosed. It's also commonly possible to open an order and then trade into your order yourself, although I haven't checked in quite a while and controls may be better now. (Doubt it.)
On a macro level, all this is mostly meaningless, and just a reason everyone ignores volume numbers for these exchanges. There's no reason for this net-neutral trading to affect market prices outside a second/minute time scale.
Most exchanges will have "liquidity partners" who have better fee structures, possibly even zero fees. Most of these arrangements are not publicly disclosed. It's also commonly possible to open an order and then trade into your order yourself, although I haven't checked in quite a while and controls may be better now. (Doubt it.)
On a macro level, all this is mostly meaningless, and just a reason everyone ignores volume numbers for these exchanges. There's no reason for this net-neutral trading to affect market prices outside a second/minute time scale.