Xiaomi Mi 10 Pro Plus popped up on our radar only recently so information about the phone is pretty scarce. And the first solid leak comes from the German TUV Rheinland certification body, which has tested its battery.
According to the listing, TUV has certified a Xiaomi phone with a 4,500 mAh battery, which is split into two main cells, each accounting for 2,250 mAh. Why is that? An educated guess would be fast charging. Most of the fast charging solutions on the market require the battery to be split at least in half to handle the ultra-fast charging speeds.
This coincides with Xiaomi's 120W fast charger that got certified last month on 3C, so it's probably safe to assume that the charger is intended for the Mi 10 Pro Plus.
Source (in Chinese)