Active functions & energy consumption
With the introduction of the latest WF-1000XM3 firmware, Sony introduced the ability to use both the DSEE HX and Equalizer functions at the same time.
Independently, both functions are active sound settings that each consume a certain level of energy. Combining them means that the headphones exert that same independent level of energy, but added up.
This causes battery life to be shorter compared to when you only use one active function.
Headphones connect alert
To alert you of the battery consumption increase, the Headphones Connect app displays a notification message when you combine the DSEE HX and Equalizer function: