Gorilla Glue

This is a bit anecdotal, speculative...but maybe some of it is interesting. Yes, colder temps can make some plants change colour. But then, that's often a sign of sub-optimal conditions. Phosphorus and carbs *can* be useful in those conditions (cellular energy/heat). Like, the closest thing to "material sunlight" is basically phosphorus, internal cellular energy (ATP). That's imo one of the reasons why roots and seeds load up on phosphorus (since they won't get good sunlight). Personally, from my few seasons of outdoor growing (even in winter), I kinda use extra carbs/sugars and phosphorus in winter.

It's not a problem. Some phenotypes can still carry different genes or colder temperatures can bring out the purple hues

I'd look at giving that thing a bit of phosphorus, calcium and sugars tbh. I mean, that discoloration does seem a bit extreme.