BEIJING—Profit growth at China’s industrial firms slowed for a sixth month as plants fought off high commodity prices, COVID-19 outbreaks, and part shortages, with an unfolding power crisis a growing threat to output and bottom-lines. Profits rose 10.1 percent on year in August to 680.3 billion yuan ($105 billion) compared with a 16.4 percent gain in July, data from China’s statistics bureau showed on Tuesday. The world’s second-biggest economy rapidly recovered from a pandemic-induced slump last year, but momentum has weakened in recent months, with its manufacturing sector facing heightened costs and production bottlenecks, and more recently, electricity rationing. Factory output rose in August at its slackest pace since July 2020, weighed by domestic COVID-19 outbreaks, high raw material prices, and a persistent shortage of parts such as semiconductors. “We expect industrial profit growth to fall further in coming months amid a notable growth slowdown in H2,” Nomura wrote in a …