UK vegan product sales (where Veganuary is most active) went down overall in 2023. This article from Nov 2023 highlights this fact and attempts to reconcile them in the context of outside economic forces.
However, we do have to consider that meat consumption is increasing and plant-based product sales are decreasing in most countries. So it is still very possible that Veganuary guarded against even worse outcomes in the UK.
@Karthik Tadepalli see my comment below:
However, we do have to consider that meat consumption is increasing and plant-based product sales are decreasing in most countries. So it is still very possible that Veganuary guarded against even worse outcomes in the UK.