Article 7 of the Convention that "In places where the coastline is extremely tortuous, or if there is a series of islands immediately adjacent to the coast, the baseline for measuring the breadth of the territorial sea may be delimited by the method of straight baselines connecting appropriate points." The delineation "should not deviate to any noticeable extent from the general direction of the coast, and the sea area within the baseline must be sufficiently close to land territory." There is a lot of international controversy over how to draw a straight baseline close to the mainland.
The main reason is that many countries tend telemarketing list to draw the baseline as far away from the coast as possible. Some countries (mainly the United States) strictly abide by the drawing method of normal baselines, so in principle, straight baselines are considered to facilitate the wanton expansion of territorial waters (and internal waters) by some countries. Whether China's straight baseline in this area satisfies the condition "should not deviate from the general direction of the coast to any significant extent" is a matter of opinion. But overall, it shouldn't be too far off. Nor is there anything wrong with this baseline in the book "Excessive Ocean Claims" compiled by the United States.
This incident reminds people of the fact that Hong Kong is not actually an island/peninsula facing the sea. After considering the territorial sea, Hong Kong is actually an area surrounded by China (mainland). Outside the waters of Hong Kong, it is not the high seas, but the The internal waters and territorial waters of the continent. The reason for this is that the Wanshan Islands, under the jurisdiction of Zhuhai, are distributed from the south to the southwest of Hong Kong, and together with mainland China, half surround Hong Kong. Therefore, the straight baseline from the mainland (Huizhou) to the Wanshan Islands is equivalent to "sealing up" Hong Kong, forming a complete encirclement. This conceptually shatters people's long-standing geographical image of Hong Kong.