The Competition and Markets Authority (CMA) said it raised consumer law concerns with the tech company last year after finding people were not being warned clearly that their phone’s performance could slow down following a 2017 software update designed to manage demands on the battery.

The iPhone maker previously came under scrutiny after it said in 2017 that software to deal with ageing batteries in iPhone 6, iPhone 6s and iPhone SE models could slow down performance. The company later apologized and lowered the price of battery replacements for affected models to $29 from $79.

“The CMA became concerned that people might have tried to repair their phone or replace it because they weren’t aware the software update had caused the handset to slow down,” it said, adding that people were not able to easily find information about the health of their phone’s battery, “which can degrade over time”.

Since the CMA raised its concerns, Apple had already started to be more upfront with iPhone users, the regulator said.

Apple was fined by Italy’s anti-trust watchdog in October last year for failing to give customers clear information about how to maintain or when to replace batteries, following complaints that the company used software updates to slow down their mobile phones.