A very very complex and controversial issue is when such things can happen at all. Those scenarios that I see are very sad. S
omething must happen that will make people stop trusting centralized exchanges, for example, hacking all exchanges at the same time, which if it happens it will be very soon.
It is also worth noting that the exchanges you are talking about have fairly mediocre liquidity (possibly except IDEX, but this is a partially centralized exchange) and this is a problem,
the speed of order execution leaves much to be desired because decentralization works this way.
But this is not the main problem, perhaps the most important problem is that servers for detailed exchanges are very expensive.