Given the variability in size and shape, it almost looks like thin canes were layered and offset, and with darker outer rings resulted in individual cloud-like appearances. This seems like a lot of work though.... Or possibly multi-ringed canes broken at varying oblique angles, shapes, and sizes - hence "flakes" as opposed to normal frit. Frit flakes are available from several manufacturers, but seem to be far removed from the beads in question.

https://www.dlartglass.com/product/detail/cbs-coatings-by-sandberg-yellow-rainbow-dichroic-glass-frit-flakes-90-coe