Does whey protein degrade over time?Based on the available research, whey protein powder has a shelf life of 9–19 months when stored under normal conditions. Most protein powders contain additives that extend the shelf life for up to 2 years.
https://www.healthline.com/nutrition/does-protein-powder-expire#shelf-life
BB date is relative to the nutritional breakdown on the contents label. If they cannot promise delivery due to temperature/ humidity influences over that timeline, that effects the BB date. It may not mix as well either.
It’s still good. Most food expiration dates are a little more than a fiction. At worst the food will be safe but texture or other qualities may not be as good. I think you have nothing to fear in regard to protein powder, especially if you are blending it into smoothies and soups.