Somebody help me understand why my Starbucks order doesn’t always cost the same

My go-to Starbucks order is a tall cold brew with non-dairy cold foam. Every time I go to a Starbucks, I either get charged $6.20 or $5.20 (Canadian) for this drink. I’m assuming it depends on how the order is being entered? Like the more expensive one is maybe just them adding a charge for making the cold foam non-dairy, vs the less expensive one is just the non-dairy cold foam as it exists on the menu (I think)?

Anyway, if anyone has any idea how the same drink is consistently charged differently across locations (or even different baristas within the same location), and what the correct price for the drink should be, please let me know! I’m too socially anxious to ask my barista irl lol