The Mendocino purps cut grows purple regardless of the temperature , so does granddaddy purple.
I had friends that grew mendo purps from seed for a couple years and I never saw anything but purple low potency buds. I’ve grown both myself indoors and outside and they are purple all the time.
Also grew the clone of forbidden fruit and it’s a little more potent then the average purple but the taste is not for me, tastes just like the old California orange plant and it’s a nice smell but not something I want to coat my mouth with.
Also the forbidden fruit grew solid purple in extremely warm outdoor conditions, the buds are purple from the start vs turning purple because of the cold or some bs trickery.
S1 seeds are not copy of the parent but rather a reshuffling of the genes present , purple being recessive makes it easy to lose that expression.