Savage has so many variations that I can't predict which models have which bolt release.

The bottom bolt release comes with the Accu-stock models.
The Accu-stock has an aluminum base and aluminum bedding that makes the stock much more rigid.
I find the bottom bolt release a bit of a PITA at times, especially when you want to remove the action, because the rear action bolt is hidden under the sliding bolt release.
But the Accu-stock provides desired rigidity and that makes it worthwhile.

I have several Accu-stock Savages.
I have a Model 10 FCP-K 308 with an Accu-stock and bottom bolt release with a standard Savage detachable mag with the mag release as part of the bottom metal.
I also have a Model 11 VT .22-250 with an Accu-stock and a bottom bolt release with the cheaper Savage detachable mag with the mag release on the mag itself.
That mag is a cheaper version that I don't like and it makes finding a replacement stock a bit of a problem.

My first Savage, a 2008 or 2009 vintage model 10 FP in .308, was purchased before the Accu-stock was readily available and it came with a synthetic stock with plastic bedding, a hidden mag and a top bolt release.
That stock flexed a lot and after I shot over 6,500 rounds and replaced the barrel. About the same time, I decided that it was time to replace the flexible stock with a Bell and Carlson adjustable stock that had an aluminum rail and aluminum pillars. The more rigid frame turned a good shooter into a great shooter.

I also have a model 12 LRP in 6.5mm Creedmoor that came with a HS-Precision stock with an aluminum frame and pillars that is my most accurate Savage and it came with standard Savage mag and a top bolt release.