I'm pretty sure for atleast T-90M, similar armor arangement is used. it's pretty obvious due to not enough space to install thick NERA on the upper glacis, I believe similar to be true for ZTZ99A as I don't think general hull armor has been modified compared to the original ZTZ99. Western tanks usually employ lower glacis armor, you'll find especially for the latest Leopard and Abrams variants that their lower glacis is heavily armored with a highly inclined(near horizontal for the Abrams) upper glacis as they are designed to take hits to the lower glacis unlike eastern tanks which are designed to take hits from upper glacis. The new Chinese MBT should be a turn from eastern design philosophy and almost definitely is designed to take hits from lower glacis like western tanks.T-80BVM do, but only because it's T-80BV at a core. T-90s and, if i understand correctly, ZTZ99A don't - their setups are different due to different geometry and thickness involved, but they're same as similar composite packages on western machines(most prominently, IFVs).
It is not a downside, quite the contrary - heavily inclined plates ensure that up to 60-70% of ru/chinese mbt upper surface is heavily armored, just because. For all modern western MBTs, it's like 20% in a best case scenario, everything else is huge, thin homogenous steel plate base. Granted, some add composite packages over crew stations since 2010s, but for east bloc MBTs it's normal to have upper hemisphere ERA since 1980s.
IMO, its not fair to compare how armored various tank's upper glacis is due to the fact that some are designed to block shots from upper glacis while others are for lower.