2008 VSC light came on

Good Afternoon,

For context, I have a 2008 Prius with 256XXX miles on it (Purchased at 171XXX). Now, I've had the car for close to four years, and from the day I bought it, the check engine light has been on. I had it checked before purchase, and it was identified as a small EV leak. My mechanic suggested the cost of repair vs the issue wasn't really worth it.

Apparently, it could be a crack in the plastic under the rear passenger seat, and the plastic piece can't be purchased individually from a complete fuel pump. (as I recall). So anyway, I've driven it for four years with great gas mileage and no issues whatsoever, engine or battery-wise. I hope to keep this car another 4-5 years, as it may be one of the best and most reliable cars I've owned.

Now on to the problem. Three days ago, my VSC light suddenly appeared on my dashboard. First time ever for this light. Took it in, and the mechanic I have now can't do such a check, and I will have to take it to a dealership (yuck), but in the process, did discover that I had a misfire in bay one, so I had a tune-up done (new sparkplugs and coil), and the car sounds/drives awesome.

But, and I know I'm long-winded - the VSC light is on, with no check engine light, no red triangle, and every search I look for only discusses when all three are on - and what the problems could be.

Research suggests: bad gas cap (*checked and ok), low battery (currently an average of 1-10degrees F here for the past few days), and the car starts perfectly every time.

So when it's just the VSC light, what issues should I next get diagnosed or be concerned about? The car is handling great on the ice and snow, traction control comes on when needed, no ABS light issues whatsoever, and the EV battery appears to be working quite well.

Suggestions regarding the VSC light?

Thanks in advance.