Low mpg

Hello, i have prius gen 2 and since this morning something strange is happening not sure if that’s the symptoms of dying hybrid battery there is no light on dashboard also no fault codes. So what the car is doing all day long the battery was on 4 bars blue (usually it goes up and down and reaches the green section almost fully charged) but not today, the other thing when i touch the throttle pedal the engine kicks in immediately and is forcing a lot ( usually the car starts only on battery until 15-20 mph then the engine kicks in) and other thing i notice is the current mpg measurement it was starting from 99.9 downhill now it starts measuring from 0.00 and sits between 5-25/30 current mpg. Also the average mpg is lower than usual i’m not sure if that’s dying hybrid battery or something else with the hybrid system.