Got to suspect that there's an almighty crash coming at some point, the central banks have printed so much money thinking Covid was going to be a complete economic catastrophe and it's not really turned out as bad as predicted.
I'm not sure I agree that the economic catastrophe isn't as bad as predicted. You can't shut down large parts of the economy for months without having a serious impact. I feel like there are still knock on effects to be felt, such as a lot of unemployment to come and a lot of junk debt to drag us down.
If I'm wrong and the economy does bounce back very quickly then I don't see how the loose policy during the pandemic will cause that to be a problem - ending up with more money than you thought you would is rarely a bad situation to be in

Unless you mean that in normalising policy they drag the markets down with them, but that would always be a problem (and one which I'm concerned that they'll try to avoid by never normalising policy again, which seems to be where we're heading) - there's no reason that they would have to do that more suddenly than if the pandemic and economic impact were as bad as / worse than feared.