Although it states "new bottle design" for 2012 it was in fact a new bottle design for the 2007 release https://www.whiskybase.com/whiskies/whisky/34416/highland-park-25-year-old that was bottled at 48.1% abv. The 2012 release was the first of many different batches at 45.7% abv. And that first release in 2012 at 45.7% abv doesn't mean that all HP 25yo of 45.7% abv are bottled in 2012. Unfortunately HP doesn't do anything to indicated the different batches that have come out over the last six years.
The HP 25yo I believe was released annually from 2012-2018 and I would estimate that the 30yo HPs of the same abv 45.7% had 3-5 different batches over the years starting in 2012 -2018 as well as I've personally seen difference in colour between two bottles of the same 45.7% abv.
Although it's well known that almost every year there was new bottles hitting the market at higher prices points in accordance with each new batch release. There is no discernible markings or stamp dating to indicate batch differences like with the Glendronach core range releases.
One really needs to have two different batches to compare the colour difference, but in a pinch, if you see a HP 25yo and its more gold colour with no hint of amber that's the one that I had and rated an 87 https://www.whiskybase.com/whiskies/whisky/79566 , the darker one is a shade or two darker and you would definitely notice it being amber in colour to a certain degree.
I had a rather disappointing HP 25yo 45.7% abv that I rated an 87, although an 87 is not a bad mark but it is when there are many different batches sitting on store shelves at $750cnd and one does not know exactly what quality of batch one is getting.