It looks like China only has "largest" if you go by raw ship count, which is probably misleading.
Really? I would expect those to be operated by the People's Armed Police, which also runs the coast guard:
https://en.wikipedia.org/wiki/Equipment_of_the_China_Coast_G...
Note that neither coast guard nor maritime militia are part of the navy, yet both have armed vessels and personnel. The coast guard in particular has larger ships than any other coast guard.
Anyway, it was hardly river patrol boats that led to this conclusion already back in 2019:
https://www.reuters.com/article/us-china-army-navy-specialre...