I was wrong and edited my response. We do have other brands. Even text messaged a coworker to double check.
Some websites (including O'Reillys) seem like they haven't updated all their listings yet to reflect this situation. I'd be willing to bet that if you went and pulled a jug of that Pennzoil High Mileage in your picture off the shelf, it says "Synthetic Blend" on the bottle just like the standard 5W-30 does now. If it doesn't then maybe O'Reillys is still clearing out old stock.
For example, here's the same part number of that Pennzoil High Mileage on Amazon.
www.amazon.com/Pennzoil-550045218-quart-5W-30-Mileage/dp/B01MF9B4EA
Marketed as synthetic blend, and says synthetic blend on the bottle.