The Samsung promotion is in conjunction with Rogers. You can't get that promo from Samsung directly even if you wanted to. Rogers is in control of their supply chain and either made the mistake of not ordering enough supply for their customer demand or (places tinfoil hat on head) is ensuring that the terms of the promotion aren't met. Yes Rogers points the finger at Samsung, but this is something between Rogers and Samsung, not you/me and Samsung. I'm a Rogers customer and not a Samsung customer. That's how.
I just spoke with Samsung as well and they informed me that they have plenty of stock and cannot understand why there is a 4 week delay in delivering these phones. I also noticed yesterday that the 512GB model has been removed as an option. I don't know if this is temporary but the Samsung rep informed me they have plenty of stock of the 512GB model. Not only that but they offer it in 5 different colors.
I'm a corporate customer with Rogers. They informed me that they only carry the 128GB phone for corporate and that due to the discounts they give, we aren't offered the free gifts. Well, i recieved my phone S21 the other day signed into the Samsung Member site and went ahead an signed up for the free gifts. They are on order now.