Despite Google announcing a "Pixel 4a Battery Performance Program" in early January, the exact issues affecting the batteries remain unclear. The update automatically reduces battery runtime and charging performance for some "Impacted Devices" and offers affected customers three options: sending in the phone for a battery replacement, receiving $50 or an equivalent amount, or getting $100 in Google Store credit towards a new Pixel phone.

In early January, Google introduced the "Pixel 4a Battery Performance Program," which stated that an automatic update would reduce battery performance for some "Impacted Devices."

However, no safety or hazard issues were mentioned, leaving users puzzled. Hector Martin, known for his work on Asahi Linux on Apple silicon and open-source Kinect drivers, examined the update's binary kernel and offered some insights.

According to Martin, the updated Pixel 4a kernel shows several peculiarities, including being built by a Google engineer on their machine rather than the official build system.

Additionally, the update alters the maximum charge voltage of specific battery profiles from 4.44 volts to 3.95 volts, significantly reducing their charging potential.

Martin suggests that the update involves two main battery profiles, identified by "ATL" and "LSN" markers, likely referring to Amperex Technology Limited and Lishen, battery cell manufacturers.

The "debug" profile for LSN-tagged batteries sees a capacity reduction from 3,080 milliamp hours (mAh) to 1,539 mAh. The most pressing question remains why Google pushed such a substantial automatic update to a phone released in 2020.

Ars Technica’s Kevin Purdy said: "No news or community reports have surfaced yet of Pixel 4a devices causing fires, or even simply failing to function, after four years. It's an automatic update with a strong fix, but for what?" Google's support page states only that the update aims to "improve the stability of their battery's performance."