You are perfectly right, so a little research brought up the following:
The Hebrew word chûg in Isaiah 40:22 often referred to three-dimensional celestial or vaulted forms rather than a flat circle, a usage also found in nearby cultures. Moreover, the Dead Sea Scrolls, especially the Great Isaiah Scroll (1QIsaᵃ) dating from the second century BC, include the entire chapter 40 of Isaiah, confirming the stability of this wording over more than two millennia.
It is still a stretch, but not so big IMHO.
Mi hai sbloccato dei ricordi dimenticati da anni!