Yes, that's true. Here's the original publication:

Jin, J-Q, et al. Hongyacha, a Naturally Caffeine-Free Tea Plant from Fujian, China. J. Agric. Food Chem. 66 (43), pp 11311–11319 (2018).

As noted in the paper, the plants still produce theobromine, which is the precursor of caffeine. Theobromine is the main alkaloid in Cacao. It is also a stimulant, but weaker than caffeine.