"However, some have argued these drops may be artificially low because participants knew the guaranteed income was temporary."

That negates the experiment. There is little incentive to quit your job or loaf when the free money is only temporary. It may also take years for the effects to be felt, as social norms break down gradually. Also, there is a big, big difference between doing this policy in a small town in Canada, where there can be social pressure to not free-load, and where you have a population with a strong cultural work ethnic, versus enacting this policy in a large, heterogeneous city.