ther eis no way in hell a 125mmL/48 gun firing a 6.5kg-7kg 560mm penetrator at 1760m/s will out perform the 120mm L/44 firing a 10kg 830mm long penetrator at 1555-1700 m/s.
Modern armor is also heavy the ZTZ-99 is lighter ergo less armor, plus the ZTZ still uses unprotected hull storage beucase it uses an autoloader from the 2A46 family of guns.
The crews will also be over worked before combat form the combination of cramped spaces, three man cres, and outdated suspsecion design and shorter hull that leads to a rougher ride.
It also uses inferior lasers, thermal vision, radios, battle management systems and is not linke dinto a brigade level satalite linked IVIS/IFF system.