It's unknown who GlobalFoundries' 14nm customers are. It could be some smartphone chip designers and potentially also AMD's ARM chips.
“GlobalFoundries announced a strategic collaboration with Samsung to deliver capacity at 14nm, one of the industry’s most advanced nodes, as Fab 8 in Malta, New York began ramping production for customers,” a statement by Mubadala reads.
The 14LPE (low-power early) and the 14LPP (low-power plus) technologies were developed by Samsung Electronics and licensed to GlobalFoundries. The manufacturing processes use FinFET transistors, but rely on back-end-of-line (BEOL) interconnects of 20nm manufacturing technology. While the two fabrication technologies do not significantly reduce costs of chips compared to the previous-generation node, they allow to boost performance of 20nm chips by 20 per cent at the same power or cut power consumption by 35 per cent without decreasing their performance or complexity.