en_tn_condensed/act/07/31.md

he marveled at the sight

Moses was surprised that the bush was not burning up in the fire. This was previously known by Stephen's audience. Alternate translation: "because the bush was not burning up" (See: rc://en/ta/man/translate/figs-explicit)

as he approached to look at it

This may mean Moses initially drew close to the bush to investigate.