I think you are on to something. It should be the Thai version of Yakult.
I'm no expert just #whysocurious and thing I should do some CSI thing and came out with:
- https://thailand.tripcanvas.co/bangkok/must-try-7-eleven/
- https://my.carousell.com/p/thailand-betagen-yoghurt-drink-114746175/
The 2nd is from Malaysia side and they are neighbouring enough so I guess we got it.