They learned from russia. It was a big failure the amass thousands of soliders and equipment near the border to ukraine in Oct/Nov 2021 and claim “it’s just a exercise”. Nobody believed that, as there were not exercises of that size in the past with that structure. China knows they have to hold drills for a plausible deniability on troops and equipment in the region, of they want to have a successfull first strike opportunity. Not having drills and equipment in the region will raise alarms when they suddenly move it there.

To dampen the war drums: On the other side, china needs the drills. China had not fought a war for 50 years. You have to realize that literally none of their generals to soldiers currently in position have ever fought in a real war. Their only experience are their drills. So maybe it is just gesture or actual training. We will know when they will try to hongkong the Taiwanese island.