The strikingly high willingness to oppose Beijing "if China uses force against Taiwan"—72.5 versus 18.6 percent—may be a reflection of the question's framing, which usually doesn't include a specific hypothetical circumstance. It's a departure from the generally ambivalent public attitude toward the perennial debate about the likelihood of war across the Taiwan Strait and the society's response.
Announcing the survey results at a press conference, TFD linked the sentiments to "China's increasingly tough attitude toward Taiwan and intensifying tension between the United States and China."