We present two new insights into the role of stellar feedback in the formation and dispersal of molecular clouds within the Galactic HII region RCW79. First, we provide evidence for the rapid dispersal of molecular material associated with RCW79, occurring on surprisingly short timescales. Second, we propose a novel explanation for the long-debated "[CII]-deficit" observed in Galactic HII bubbles, focusing on the young, compact HII region S144, located within the dust and gas ring of RCW79. Through large-scale mapping of the [CII] 158 µm line with the SOFIA FEEDBACK program, we identify high-velocity gas (up ±25 km s⁻¹) associated with cloud fragmentation and erosion. These high-velocity outflows, or "chimneys," represent ablated material that may contribute to the rapid dispersal of the host molecular cloud. This highlights the profound impact of stellar feedback in reshaping the surrounding environment. Focusing on S144, located in the southeastern ring of RCW79, we identify an O star driving a compact HII region bubble. At this remarkably early evolutionary stage, the bubble interior remains "filled" with ionized carbon, and self-absorption effects mimic a [CII]-deficit. Once these effects are accounted for, the apparent deficit disappears.These findings underline the efficiency of stellar feedback both in destroying natal molecular clouds and in influencing the interpretation of line emission in young star-forming regions. They provide new insights into early stellar feedback processes, spanning high-velocity ablation flows to compact HII bubbles, prior to significant wind-driven expansion.
