What is the ruling on the Dhuhr prayer performed in China, which begins with the imam reciting aloud for 5 minutes, followed by a sermon of 20 to 40 minutes, then the congregants pray 4 separate rak’ahs individually, after which the imam delivers a brief sermon, and then the prayer is established?

It is not surprising that innovations (bidʻah) are widespread among Muslim populations that have been subjected to oppression and systematic ignorance by communists. Persistently reciting specific surahs or verses, or delivering a sermon before the Friday khutbah (definition), are innovations. However, these do not prevent one for whom Friday prayer is obligatory from attending it with them. You are required to perform the prayer and attend its khutbah. You are not obliged to attend the sermon or recitation they perform before it. Studying is not an excuse for missing the Friday prayer.