not credible ones. google "ex post facto law" if you are confused about this.

No, all credible ones work by updating "rules" on the fly. That's literally how most laws are made in general. Something bad happens and appointed agencies and legislators rule and/or pass laws to cover that bad thing from happening again. Ex post facto only deals with retroactive aspects. Which isn't happening here. Just because the government acted one way in the past and not the same way in this instance does not equate to the retroactive definition of ex facto law.