Yes, they now do. 2.0 at least, not 1.5 There's also plenty of people reselling as well. Here's their official link.
You can subscribe 5 times (60 bottles a month) to it to get a 15% discount.
You were probably looking at listings from unauthorized resellers, which is a common mistake because Amazon does fuck-all to clarify if you're looking at the real listing or not.
You're better off bookmarking the correct page since Amazon makes it so difficult to find: https://www.amazon.com/gp/product/B01EUEIL3E/
Any other 2.0 listing you might find is an unauthorized reseller, and at the current time any listing for any Soylent product other than 2.0 is also unauthorized. They did have bars officially listed for a while, and I think they're working on Coffiest. Also, if the page doesn't say "Amazon Launchpad", you're definitely in the wrong place.
The base Amazon price and the base website price are always identical. The Soylent website offers a 5% discount for subscriptions; Amazon offers a base 5% discount for subscriptions but it rises to 15% if you have 5 or more Subscribe & Save items shipped to you in your monthly shipment. You can do this with 5 boxes of 2.0, but you have to do 5 individual subscriptions; it won't count if you do 1 subscription with a quantity of 5.
You can get the same 15% discount on the Soylent website with the 5% subscription discount + 10% coupon discount; there are permanent 10% coupon codes and occasional larger coupon codes, but they only apply to the first shipment of the subscription so you have to constantly cancel and re-subscribe. Amazon is a lot simpler, plus a lot of people have credit cards that give cash back on Amazon purchases.
What ever that listing was it is not one I would use, unless it is new Soylent doesn't come in vanilla, except the Cafe version.
These are the link with Amazon setup, for prime, subscribe and save and 20% off first order coupon.
Cafe varieties https://www.amazon.com/dp/B01IRFB0G2/
Original varieties https://www.amazon.com/dp/B01EUEIL3E/