Because every vendor makes their own up and most of them do a very shitty and inconsistent job of it with multiple vendors selling what appears to be exactly the same product (same name, labelling etc) but the ratios of the compounds used in relation to the PG/VG solution in the case of C-liquids but even the actual compounds used in any branded products. Try some of the sponsored ;links on here, researchchemistry.co.uk have some they make themselves I believe and I’ve had other goods from there before ancd been as happy as if I’d bought from any other of my trusted vendors but in all honesty I have never tried their c-liquids.
