I don't have the new iteration so can't comment directly however mine from the very first batch ran at +20 spd its whole life. I was never happy with that performance and must admit I wouldn't be happy with the performance yours is returning either.
My Dagaz which also uses the Miyota is returning 4spd.
My SARB017 with a 6R15 auto movement runs at -4s per day. I did have it regulated when the new crystal was fitted though.
+16 SPD but it doesn't bother me because it's reset every Sunday so I know where I'm up to during the week. Besides, I'm always early for appointments so accuracy isn't critical.
I haven't checked recently but when I first got mine, it was running at greater than +10 spd but when I started keeping it crown up at night as suggested by someone here, it settled down to a better +2 spd.
That being said, I recently got a cheap jaxa wrench and have regulated a couple of my worse watches so if this one was not within 10 seconds per day, I'd have no qualms about opening it up and adjusting it.
Screenshot_20190523-174727.jpgScreenshot_20190523-174733.jpg
My original 40mm from a few years ago and my 36mm both gain several seconds per day, so I set them 30secs slow when winding to wear, and they run accurately enough for the time I wear them.
F.T.F.A.
I can't complain: my PRS-25 36mm has gained two seconds in two days.