Grafted from a piece of chimera. That is why profuse pupping.Branches may or may not form.

Chimera : Hylocalycium (Hylocereus undatus + Gymnocalycium mihanovichii forma rubra “cv. Red Hibotan” was first described in 1987.

The scion is from a chimera though it is showing more red, in time other characters may emerge. You will see a mix of characters of both.

"Graft Chimera (synonym: Graft Hybrid) are cellular hybrids between representatives of two or more named genera. They are a rare phenomenon arising exclusively in cultivation where two species, frequently of two distinct genera, are grafted together.