Both plants have purple stems not just leaf but some along the main stems. Looking online it could be phosphorus, magnesium or light stress due to LST. Also read iron and zinc toxicity can lead to P lockout. Probably my fault due to giving Acti Vera which contains Fe/Zn without supplementing NPK.
Will stop Acti Vera for now, given bit of early Bloom as it's the highest thing I've got for P (2-6.5-4.3) Bloom is recommended from 10/12 of flowering. Fish mix which hardly contains P (5-1-4)
Starting the flowering stage.
@Weedman4200, Thanks I have upped the bloom feed to max 4ml, grew this strain back in 2019 (my 2nd grow) and the leaves had turned a dark blue/ black with a much stronger smell, probably a different variant.