I'd pick up on what filo says - Stats for Lefties is being thoroughly dishonest, again, not making it clear that this an unrepresentative sample of less than 200 18 to 24 year olds from what was a representative sample of GB adults.
edit: this is from Survation's Chris Curtis if you want to get a sense of how dishonest putting that up like that is,
"Average voting intention of 18-24s from most recent @YouGov @RedfieldWilton @SavantaComRes polls:
Con 23
Lab 48
LD 8
Grn 15
Average voting intention of 18-34s from most recent @OpiniumResearch @Survation @IpsosMORI polls:
Con 24
Lab 48
LD 9
Grn 11"
To what you're saying, there's evidence for some movement from Labour to Greens since the general election but that's pretty normal. Whether it's an outsized number to reasonable comparisons will probably be clearer over the next few months and the locals can be picked over. Another big part of it is that the Greens are challenging the Lib Dems for the third party space in parts of the country. Whether that holds up outside of specific wards and across entire constituencies seems a harder question, especially given the success the Greens are having in replacing the Lib Dems at very localised messaging.
Poll