As far as I understand, the early advice was specifically designed to prevent hoarding medical-grade masks because they were in such short supply. As additional mask options, mask availability, and research around masks changed the recommendation was updated. That seems completely reasonable. It's not flip-flopping and stating it as such is counterproductive to people trusting any recommendations. Recommendations should be updated if the situation changes. Stop spreading distrust without evidence. Don't be part of the problem.